What are the best ways to teach children about God in the hopes that they might become a child of God ?
By the Word
In our Sunday school children’s program, we require the Word of God to be read during their activities. In doing so, we are exposing our children to the Word of God, and to the power that comes with hearing the gospel. The Apostle Paul wrote, “For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek” (Rom 1:16), so the Word of God has the power to save. Paul adds, “For the word of the cross is folly to those who are perishing, but to us who are being saved it is the power of God” (1st Cor 1:18). It might seem folly to children too, at least at first, but the repeated exposure to the Word of God can make fertile ground for the Spirit of God to make them children of God, since “faith comes from hearing, and hearing through the word of Christ” (Rom 10:17), so how will they ever hear unless it is from their teachers, but first and foremost, their parents.
The first responsibility begins at home. Parents make great teachers and children make great students because they’re very much like a sponge. They will soak in whatever they are exposed to, good or bad, and even if it doesn’t appear on the surface, you know it’s down in there. It may take years for it to surface, but I don’t believe an early exposure to the Word of God ever disappears. God’s Word will have its way with them, one way or the other (Isaiah 55:11). The point is, children will only be fed what they receive from their parents, but parents are competing with the world, so a solid, early foundation of the Bible and biblical lessons are even more important. If your children don’t learn about God from you, they’ll learn about Him from someone else…and it might not be good or true. From my experience, evangelical children who are spiritually neglected make fertile ground for two extremes; joining a cult and running off into the “far country” (Luke 15:13). No parent wants their child living in a pig pen or a cult, so pray, model, read, and live it out.
Real Life Examples
Of course parents and grandparents, as well as aunts and uncles, should always set a good example because we believe more is caught than is taught, so living out what the Bible teaches  is often more effective than teaching them to do the right thing, although that should not be left out either. What I love are the “teachable moments” that come in life; a moral decision a movie character has to make; a death in the family that shakes everyone to the core; a story where someone goes from being homeless to getting a college degree. It is so easy to find biblical accounts and examples in the world that can plug those lessons into how they should react to similar situations in life. David was anointed as king, but King Saul still sat on the throne and sought David relentlessly, trying to kill him, and when David had a chance to kill Saul, he didn’t. He waited on God and trusted His timing. David respected authority. A child might be in a position to “pay back” someone who might actually deserve it, but what a great lesson on waiting upon God to bring justice. Paul’s words may help them, as he wrote we are to “never avenge yourselves, but leave it to the wrath of God, for it is written, “Vengeance is mine, I will repay, says the Lord.” To the contrary, “if your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by so doing you will heap burning coals on his head” (Rom 12:19-20). In fact, if the child has a Goliath in their life, like a bully, we are to love our enemies and pray for them that persecute us (Matt 5:44).
When my son was young, we helped out at a homeless shelter, and at first, he was a bit fearful, so he stayed behind the counter with me, but then he started feeling a sense of security and wanted to start helping people, so he joined with us in helping. I reminded him that it is not we who do these good works, but the Spirit of God that motivates us or enables us to do good works that God has planned for us to do (Eph 2:10). I reminded him that whatever we do, we must give God the glory or all of our good deeds are worthless. Children too, like the creation itself, were made to glorify God, and so I reminded him of that. Their lives are to glorify God and never glorify self. It is all about Him. Our works are to be seen by God and not man. There are so many examples that you can pull from the Bible about people doing good but not bringing attention to themselves. First and foremost, Jesus, Who raised the dead, made the lame to walk, the blind to see, and deaf and mute to hear and speak, but Jesus usually said, “tell no one” (Mark 7:36, 8:30, 9:9), so even Jesus sought not His own fame, but sought to give God the glory.
Make it a family habit to have Bible reading time and then a question and answer session. If no one asks a question, come up with one yourself, like “Tell me why you think David might have been afraid of Goliath?” Open-ended questions are always better than questions that only require a yes or no. Ask them if they can relate the account in the Bible to something that’s happened or is happening to them. Do they have a Goliath in their classroom who is a bully? Do you see that a lot of students are getting away with cheating? A great way to teach children about God is to read them some brief historical accounts of famous Christians like William Wilberforce or John Newton, who had to make critical decisions based upon their faith. Read how God dramatically changed people’s lives. Tie in their decisions to their biblical convictions. And never underestimate a child because we can’t always tell whether a child’s too young or not to be saved. It’s very important to have this be 100% of the child’s decision. Pressuring children into being saved puts the child at risk of becoming a false convert. Just as long as the child is brought to repentance by God and understands what it means to believe or trust in Christ, they can be saved. The gospel is so simple that even young children can understand, and many do, and that is a primary reason we must teach our children, our grandchildren, our nieces and nephews, and anyone that we have contact with…young or old, that they too can be saved.
Here is some related reading for you: Children’t Bible Stories 
Resource – Scripture quotations are from The Holy Bible, English Standard Version® (ESV®), Crossway Bibles. (2007). ESV: Study Bible : English standard version. Wheaton, Ill: Crossway Bibles. Used by permission. All rights reserved.