You may not be able to teach your small son very much about God right now -- but you can teach him something, and that should be your goal. After all, you don't stop feeding him healthy food just because he doesn't understand very much about nutrition, do you?
How should we teach our children about God? First, we should teach them simply and yet clearly. For example, teaching them to memorize a simple prayer of thanks they can say before meals will help them understand God's care for them. Reading them a brief selection from a children's Bible storybook will help them understand God's love for us. And praying with them before they go to bed will help them realize that God is real, even if we can't see Him.
Then we should teach our children by our example. Will they see that God makes a difference in our lives -- in the way we treat others, in our honesty, in our speech, in the way we use our time and money, and so forth? Will they learn that our church is important to us? The Bible says, "The righteous man leads a blameless life; blessed are his children after him" (Proverbs 20:7).
Make Christ the center and foundation of your life -- and of your family. Then ask Him to show you how to help your son discover not only that you love him, but that God loves him, too.