The whole idea that God existed before anything else (he is outside of and indeed the creator of space, time, energy and matter) and that he has always existed (there is no "before God") and will always exist is difficult enough for humans to understand. Closely related to this reality about God is the difficulty in understanding how exactly God is the Creator and also how he is always in control. I've thought of a simple typical experience that everyone has seen, which can help to understand by putting one in the right mindset.
Think back to a time when you have opened the window on a warm day, and a breeze blows into the window, stirring and moving the curtains. Well, the first step to understanding God is realizing that God is not standing there waving the curtains back and forth for you.
LOL! I know you are saying, well, I never thought that he was! Yes, but the misdirected human understanding of God is not too far from thinking that. The idea that "everything" has a message (from God or "someone else," like a deceased loved one or a "spirit") is only one step away from thinking that God is standing there and it is his "control" that makes the curtains move back and forth in the breeze.
Why is there this confusion? People get confused with three aspects of God's power: 1) his being the Creator 2) his being "in control" and 3) everything that happens is "God's will." This is why I realized this simple analogy will help you to understand each of these three aspects of God's power.
God created the universe, including everything in it, such as the sun which provides the warm day, the earth and the humans upon it, the weather, and thus the wind that moves the curtains. During God's creation God maintains total control over all that is created, and being All Knowing, God perfects his creation so that it continues to develop and function the way he intended. Thus God is in control because he shaped the material of his creation so that it has natural law and forces that support ongoing existence (such as atomic structures, the movement of light, the existence of mass and gravity, the effects of rotation and so forth). This is why the curtains move and God does not have to stand there and invisibly make them flap back and forth for you, ha. The curtains move because God created the materials and the forces (nature laws) of the structure of the universe and then he let them go. It's not like God has to "try it out," because remember, he is All Knowing. When God declared in the Bible that his creation is "good," that is what he meant, that he created all that the universe (and life within it) needed for it to now run on its own.
So when you heat a pot of water over an open fire, God is not having to rub the water molecules together for you so that the water becomes warm and then hot, any more than God is having to combust each of the molecules of the wood so that it would burn. Water heats over a flame because God created the infrastructure and the natural forces that would be "good," as in effective and self sustaining. Another example, gravity works not because God has to put his hand over each object and person and hold them down onto the earth, ha.
Back to our example, God created and controls the waving of the curtain in the breeze because God created time, matter and energy, and thus the forces that align and motivate them in predictable behavior of physics and science. So God created the "raw materials" for the waving of the curtain (the sun, the earth, fibers and wood, people smart enough to build houses with windows and curtains, weather including the development of wind when the temperature and pressure gradients are right, etc). When we say that God is in control, what we should mean is that everything he put into place is functioning authentically and predictably, just as it should. I've written about this before in the blog but just to remind you, an unforeseen and tragic automobile accident where there is a loss of life is in God's control not because God reaches out and pushes one car into another, but because God created a universe where if two heavy objects collide the materials within react according to physics in a predictable way.
Now that you understand, at least on a gut level, through these simple examples, how God 1) creates and 2) controls (to put it simply, he creates the raw materials and the "rules" by which creation continues onward and interacts within itself) you can better understand the levels at which something is God's will. Let's start with returning to the open window with the warm breeze that waves the curtains.
It was God's will that he decided to create a universe in the first place. It is God's will that he created in the way that he did, that it is stable and consistent, but with growth, change and movement. It is God's will that living beings will find what they need to sustain life (such as light, warmth and air). It is God's will that some beings, humans mostly but some animals too, are smart enough to shape their own dwellings. It is God's will that humans benefit from wise decisions (seeking shelter in their dwellings when weather is harsh), but it is also God's will that the power of bad weather, for example, does not suddenly halt and become benign whenever someone makes a bad decision (such as taking a boat out into the stormy seas, and remember, Jesus had to miraculously intervene when the Apostles were set upon by a storm at sea). So it is God's will that all in all, he very very VERY rarely upends and overturns the laws by which the universe of time, energy and matter operates in order to miraculously sustain someone in a bad situation, of their making or not (such as a natural disaster). It is further God's will that humans (and animals) feel pleasure, including aesthetics, in life. Thus it is God's will that the warm breeze feels good, the sun uplifts one's spirit, and the waving of the curtain in the breeze feels homey and aesthetically pleasing. Likewise, if one misjudges and makes an error (such as putting a fragile vase in front of an open window with a strong breeze, and it is knocked down), it is God's will that oops, natural forces continue to work as expected. God neither knocks down the vase nor "makes you feel bad," but that is the natural outcome of the small actions in life as time, energy, matter and human free choice interact.
So when someone devout says, usually after a sad event or loss, that it is "God's will," that is actually not a simplistic observation. It is, rather, the wise summation of the creative, by God, the controlling, by God, and free choice, by humans or by happenstance, outcome for all of the above to exist at all as a result of God's will. Yes, then, when a person dies, his or her "time had come" and it is "God's will," but the slippery slope is that one must not imagine that God is pushing some baby into a swimming pool, or cramming one car into another, or "giving" a person cancer, etc. God created all those materials, energies and potentialities (according to free choice and situations) and it is his will that with very rare exceptions, the rewards or the consequences naturally result. What do I mean by potentialities? Well, I blogged about one example before, which is being around potentially cancer causing smoke. It's not like God has to, nor is it in his nature, to reach inside someone and "give" them "cancer." Further, God does not make a person crave smoking cigarettes. All those potentialities are a matter of chemistry, physics, human genetics and human free choice. It is God's will that life has limitations and dangers, but it is also God's will that humans can seek ways to maximize the benefits of well being. Water is great, and swimming is great, but lack of a fence and a watchful parent over a baby near water is unwise. Likewise tobacco might be pleasurable to smoke in a cigarette but the problem develops when it is done to excess and becomes a habit that stimulates potential cancer in one's self or second hand in others.
So when a person mourns that the loss of a loved one is "God's will," that person is being pious and correct if they realize, as most have done so before these past few generations, that the life that one is given is unpredictable, that life is robust and forgiving while at the same time fragile and subject to defect, and that it is indeed the person's "time" because God will not intervene (except in those rare miraculous circumstances) when the known factors of a person's potential demise intersect. An example of an intersection is 1) smoking to excess 2) being of weak health or prone to easy damage 3) unable or unwilling to receive treatment. God does not 1) make the person smoke to excess 2) "give" him or her bad genes or 3) deprive them of treatment or give them a negative and bad attitude about available treatment. You see what I mean?
Moderns have become, for reasons I've discussed before 1) paranoid 2) narcissistic 3) excessively "magical" thinking and 4) disbelieving in the ultimate goodness of God and God alone. Thus there has been (and I pray that this is changing) an increasing obsession that somehow long life and wonderfulness has been guaranteed to everyone (and some of that is the "deeds" over grace error of thought) and that when an intersection of natural law and situations/human choices occurs that God (or "alien" or "other" forces) have "singled out" a person or group for hardship. That's not only wrong but it's dangerous because one then discards not only authentic belief in God but one also discards common sense and proper survival instincts and thinking.
Imagine if someone actually thought that when he opened the window and the sun shone and the breeze blew and the curtains waved that God was just standing there, waving that big peacock feather fan at him, turning on the tanning lamp and just giving him his own personal spa treatment. You'd think that person was crazy, right? Well, as I said, unfortunately many people have gotten on that slippery slope as they should have known better and worse, raised their children or taught their students that entire warped mindset. Thus many young people are paranoid and narcissistic because they feel so manipulated and at the behest of an arbitrary world filled with "unfairness" and "forces" that must be appeased/controlled! By the way, when I say "unfairness" I mean "not fair" by some human standard; I don't mean unjust because then I'd be in total agreement: the world is filled with human injustice and unrighteousness. But the word "fair" in popular thought (separate from political or legal thought) has come to mean that one's life seems disproportionate to one's expectations, and thus subject to some mysterious dispensation of favor or punishment. That kind of thinking results in attitudes such as, just for an easy example, that the life providing process by which a human body makes and stores fat is somehow bad and must be tamed. Um, no one would be alive if the body could not make and store fat, duh. But this paranoid separation from reality (both faith reality and secular reality) results in some messed up thinking.
I yearn for the time when people understood this, as they all did, prior to the last fifty years or so (with a few lunatic exceptions, of course, none of whom I need to name here).
Anyway, rather than get into that whole mess (again) in discussion, I'd rather leave you with this hopefully helpful simple analogy for understanding how God does indeed create, control and exert his will.