You can't understand God if you allow certain stereotyped assumptions about what would be "logical" for God to "do" to creep into your understanding of God overall or in specific instances. The one I want to discuss now is the human tendency to think that with time comes greater clarity and sophistication of revelation. So there is the assumption that God "explains" "more" throughout human faith history. Muslims tend to hang their hat on this assumption quite a bit, and I mean no disrespect. But many think that God is revealed just a little bit at first, and then more, and then more, and Prophets come along of greater and greater progressive power and clarity, building on each other before to a crescendo and completion of understanding. Well, that is not true and it is not Biblically supported nor is that a safe assumption in the Qur'an either.
You can tell this is not true both from a human nature understanding and by examining the scripture. First, the human nature point of view. While humans presumably progress in the gained detail of scientific knowledge, one cannot actually map a similar steady progression the understanding of God. For example, humans may know more about the DNA of tomatoes than at any time in human history, yet they cannot find the source, even narrowing it down to the country, of an incidence of contamination. So this is an example of how technical knowledge may progress but the application regresses. Likewise, the more self confidence that humans have in their "modern" skills and knowledge, the more they question and allow to fall away the genuine knowledge of God that he has revealed and ancestors have carefully preserved and added to. So simple observation of humans demonstrate that while they gain increasingly precise bodies of knowledge about specific areas of technical study, rather than seeing a progressive virtue of their application, you often see a regression. So it is inaccurate to assume that God would progressively reveal based on "that's how humans assume it is done," because critical analysis shows that humans don't actually do that in truth themselves.
Secondly, the Bible documents how God has chosen to reveal himself over time. If you look at it with new eyesight, as I offer to you here, and look at each instance for its "additive complexity," you will find that no, God is not "building" from "simple to complex" or from "more hidden to more revealed" or from "preliminary to finalized" gradations of understanding.
Think about the complexity of information and interaction provided to Adam and Eve and their direct offspring. While the Bible does not document it, it is obvious that God converses with them as being physically present (they hear him walking in the garden). Adam names the animals and has obviously a high level of knowledge about his own origin and God's relationship with humans. We know this because Abel, his son, is able to perform perfect ritual and sacrifice that pleases God so much that Abel's brother Cain kills him. Is it not obvious that the relationship with God and knowledge of him started out at a zenith of intensity and complexity, even after the departure from the Garden? The Qur'an agrees, documenting that God brings angels to "meet" Adam and bow to him because angels should adore what God has created and loves. So the very first encounter was not the tentative information sharing of God "on a first date" to use a silly but illustrative analogy, where only simple and tentative information is shared.So read each event that proceeds from the first and as an exercise, think about how complex or simple is the interaction with God, and does it build progressively on the body of knowledge and insight about God? The answer will soon be obvious, which it does not.
For example, there is obviously an enormous spike in the amount of specific information given to humans when God uses Moses for decades to convey his commandments, law and even advice, with God actually dwelling in a physical presence in their midst. Yet do the people understand God more? Actually, no. They understand what God expects of them more. But one could argue that Adam understood God's fundamental nature much more than did the Israelites under the command of Moses and Aaron. Think about it.
Likewise, the greatest prophets were often great because they prophesied momentous events to come, such as the fall of the Temple, the captivity of the Israelites, and the coming of the Messiah. But did any of those prophecies actually illuminate how to understand and comprehend God and his will more clearly? No. However, scripture accumulated that does shed light on how to better understand God, but it is not sequential and progressive in nature. It is in the wisdom books, and it is learned between the lines by wisely studying the interactions between God and those closest to him, such as King David. Therefore bodies of work such as the Psalms are more illuminating of the nature of God than a progressive succession of Prophets, who are holy and wise, but targeted in their areas of intention and ministry.
The obvious culmination of understanding God comes with the Messiah, Jesus Christ. Being born of the Holy Spirit over Mary and also in communion with God, Jesus is called the New Adam not just because of his power to redeem the sin of Adam. Jesus is the one who restores a direct contact with understanding the nature of God in a way that Adam possessed. Only someone who 'has actually been with God' can begin to understand as much as a human can understand God, and therefore interpret and explain God to humans. Adam was created by God and dwelled with him in the place that God made for him. Jesus was begotten of the Holy Spirit of God. The breath of God's nature is within Jesus, and he was born of it. No one can understand God better than someone who is of the same substance of God.
Therefore, Jesus is the "epitome" of the capability of anyone in a human body to understand God. The Prophets and Fathers were not given a little bit of understanding, and then a little more, and then a little more, and then a little more, finally culminating in Jesus. God revealed himself in each instance throughout faith history in a consistent (as far as his oneness, his reality and his expectations of humans) way, but not at all in a sequential or increasing sophistication of revealing way. It is not at all as if each Prophet added to understanding of God. In fact, during the captivity, it was quite an arid time for increased understanding of God, since the people were so persistently disobedient and disbelieving of what they had already been given.
So just as Adam was "one of a kind" in his relationship with God (as evidenced by his son Abel's ability to perform perfect offering and sacrifice to God), Jesus obviously was not the progressive culmination of human prophets and their building of lore, but rather the one who fulfilled the lore and the prophesies plus brought perfect understanding of God. Adam "had" God but lost him. Jesus brought God and a New Covenant back to humanity. Being born in a human body but of the substance of the Holy Spirit, Jesus had a truly internal understanding of God, being of the same substance through the Holy Spirit, that has never been and never will be repeated. Therefore one must take very seriously and have complete confidence in Jesus' understanding of God and his teachings of what God intends and what is his will in all matters.
So with all due respect, just as Christians err in sometimes forgetting that the goal is God through Jesus, Muslims have a similar error in thinking that the "final" Prophet (PBUH) is a culmination of perfected teaching. The teaching is perfect, but it is not the end result of an increasing "accuracy" or "complexity" or "clarity." The Qur'an is perfect because as I mentioned above, God is always consistent in his nature and therefore his expectations of humans. The Prophet is indeed "the last" of the Prophets because in the series of time that has transpired, he is the last to reiterate the faith of the descendants of Abraham to the people. The Prophet did not come to progressively build and correct what had gone before. He came to "round up" and bring into the family the descendants of Abraham who had not received God. So the Prophet reconnected what would be called the Muslim lineage back to the fold of the one true God. The Prophet did not "succeed" Jesus in any way, shape or form. Further, Muslims continue to misunderstand that the one that Jesus promised was the Holy Spirit, and not a human. Jesus did not prophesy the Prophet and I mean absolutely no disrespect. Why would Jesus have to prophesy him since God saw fit to send the Prophet?
That is what I mean by humans understandable and well meant, but erroneous, assumption that the most "recent" communication by God "builds on" "enhances" or "replaces" or "corrects" what has gone before. But did the Prophet "correct" anything that Moses revealed? Surely not. The Prophet was sent to save the people who had through no fault of their own been splintered from the monotheistic relationship with the One true God of their forefathers. That is why so much of the Qur'an is revalidation of what had gone before, not editing, improvement or replacement.
Modern people tend to misunderstand God's perspective in so many ways. God always seeks to balance "free will," so that humans are not robots but loved children who can make their own decisions, with the desire to save as many souls as possible. Not to build the largest mosques or churches at a time, or to have the highest percentage of one of the faiths, but to sweep as many people alive at any given time onto the good road of knowing and obeying him, leading to their reward in Paradise. God is perfectly capable of doing this through more complicated means than people understand. It's not like God launches one religion and then if it does not have fine enough 'results' then he launches another religion.
God in his all knowing and all seeing perfection of awareness and wisdom sees at all times "how humans are doing." That is obvious because you can read in the Bible and the Qur'an how he has had to send angelic messengers or Prophets at crucial times in order to steer people in the correct direction. Sometimes people respond and sometimes they do not. And God does not sit back and go, "oh well, these children who I love have never heard my word, hmmm, let's hope that Christianity makes it to them sometime in the next thousand years." No, in his love, mercy and wisdom he gifted the Prophet with his knowledge and the Qur'an. God does not want to "wait" and see how many hear his word and follow his Prophets, and just shrug when centuries go by and people do not have the chance to know him. God will act. Further, the Holy Spirit moves constantly among all people, including those who were not among the chosen of the Book, or of Christianity, or of Islam. The Holy Spirit moves to create the desire to find out about God and to convert. Sometimes evangelists would arrive in places to find that they had almost been expected, such is the thirst to know God, through either the Bible or the Qur'an.
THAT is how to best ground in a firm basis your desire to understand God. God is not treating humans like a classroom where you start with learning to count and progress to graduation from secondary school and then college. God "started out" with an enormity of good will and intimacy with Adam and his family, where people who could not read and write knew God more than anyone alive for many centuries and as I pointed out, in some ways, not until Jesus Christ himself who had the fullness of understanding that comes from the shared substance of the Holy Spirit in his birth.
As you can imagine there is a lot more that I can say, but my intention was to invite those of you who love the Bible and the Qur'an and desire to know and serve God with all your hearts to look at what I've said with new eyes. I should not have taken away any of your confidence in your faith, but rather, expanded it, in perhaps a slightly uncomfortable way, because it is easy and safe to assume that God thinks and acts like humans do, but he does not. So if you are a little uneasy, it is good, because it means that you have expanded your potential for truly understanding God, and sometimes a wider horizon is a bit disconcerting! I promise you that if you read any part of the Bible, or the Qur'an, and now think about how each event is truly of its own significance, and study how God chooses what to do and what to reveal, you will find more richness, not less. You should have enormous comfort that God has always sought the deepest and most intimate relationship with humans, rather than increasingly strict and angry tasks that "students" who are exposed to "more and more study" are supposed to know until they have the "final testing and examination". Adam knew more about God than just about anyone until Moses, and then most assuredly Jesus Christ. This takes nothing away from the holiness of Abraham, for example. And as another example, think about Joseph, exiled to Egypt as a slave, but eventually saving the country and his own people from starvation through the grace of God. God gifted Joseph with prophecy and blessings. However, Joseph did not represent the next progressive "stepping stone" in understanding God. That would come with Moses. Just because a Prophet acts on behalf of God and has grace and charisms from God does not mean that the "most recent" Prophet is improving and perfecting the knowledge of the Prophet before him, and certainly is not progressively adding to a linearly accumulating body of knowledge about God. But now you can see that each generation contributes to the relationship with God in their own way, and not necessarily in a linear pattern of increasing complexity, correction or "improved accuracy and truth." God is consistently always the truth and never pulls out the rug under humans by issuing "corrections" or "now you are going to get the 'real' story updates."
Anyway, this is enough for this one blog posting. I hope that you contemplate and discuss it, and that it is fruitful to you and helpful. It is an essential step in resolving differences in ecumenical dialogue to come.