This is the plainest and simplest way to understand the direct path toward faith in God.
1. Truth: knowledge that he exists
This is supposed to be presented to children at the youngest age, at the same time that they understand who they are, who their parents and other relatives are, and identity of people in general. Children need to be told that God exists, but cannot be seen. When children ask how do we know God exists, explain that many people have seen and spoken with him a long time ago and they left the book (the Bible) that states that he is there and what happened. Children of Islam, the same understanding is given to children about God's existence and the book of the Qur'an. As Christian children grow older they start to understand that God proved his existence in latter years by sending his Son Jesus Christ.
You see, you cannot have faith or reach God if you don't accept that people a lot closer to God than you have testified to his existence and left records of that in the Bible and the Qur'an. If you try to "have faith" or "understand if God exists" you are unlikely to succeed because you are starting with the unspoken assumption that you are smarter or closer to the truth than the authors of the Bible and the Qur'an, and you most certainly are not. This is why you cannot "logic" or "faith" your way to God. You have to first understand that impeccable witness has been given through thousands of years by people who know and saw with their own eyes. No one can duplicate or surpass that; you simply have to accept the facts of the written Word.
2. Love and goodness: You understand that all love and goodness comes ultimately from God, not humans, plants, animals or imaginary beings.
Thus immediately upon accepting the facts, the truth, that God exists, one understands, accepts and embraces that God IS love, that God is all the goodness that ever existed and could ever exist. This is where the child (and those late to finding God) accept the gift of love and give all glory and credit to God for the goodness of creation, the goodness of life, and any blessings. In other words, one understands God's true being, his identity. One can therefore start to develop one's own personal relationship with God. Children start by accompanying their parents in prayer and worship.
3. Consequences of disbelief and sin: You understand that achieving heaven and being with God in eternity is by no means guaranteed, and that sin displeases God mightily and he will react accordingly.
This is something that teenagers, young adults and often extended to middle age adults grapple with but absolutely must not deny or dodge. Children start to learn this from parents and also their worship community, as they recognize right from wrong in general, and what sin is and how it aggrieves God specifically. Sin is understood to be not only an offense against God but also working in opposition and contradiction to what God alone understands is good for each person and for humanity in general. That understanding often comes with age, but no one is guaranteed the time to "find that out in one's own time" so again, children when they reach appropriate ages of understanding must be taught the balance between a loving and forgiving God, but the grave error in taking that for granted and indeed jeopardizing one's relationship with God.
That third stage is the first of the seven gifts of the Holy Spirit, "Fear of the Lord."
Notice that this foundational gift, which is needed before other gifts can truly be received from the Holy Spirit, is thus the first step in the Gifts of the Holy Spirit, but the third step in having faith in God. Faith in God requires: acceptance of his truth of existence, acceptance of his love and goodness, and knowledge of the consequences of sin and disbelief. When you have that "package" of those three steps, you have faith in God, and you are ready to start receiving the unmerited grace of the gifts of the Holy Spirit, the first of which is "Fear of the Lord."
I hope this has been helpful to parents, children, young people, caregivers, preachers, those responsible for faith formation, and those who are patching and repairing their faith journey, which they may have been deprived of in total, or had missteps along the way.