Yes, it is worth it to teach young children about God and the Bible. They may not understand everything we say, but they'll begin to realize that God is real, and that He is important to us.
After all, if you fail to teach them anything about God during those early years, what will they come to believe? They'll come to believe that only things you can see and touch are real -- and anything else (including God) isn't. They'll also come to believe that God must not be very important, since we haven't bothered to teach them about Him.
But God is real -- more real and more lasting than anything in the world around us -- and our children need to know this. They also need to know that He made them, and He is their Heavenly Father. They need too to know that He loves them, and wants to help them and be with them. Most of all, they need to know that Jesus gave His life for them so they can be with Him in heaven forever.
Pray for your children, and pray with them, also. In addition, ask God to help you teach them about His love; a Bible story book for children can help you do this (you can get one at your local Christian bookstore). The Bible says, "Impress them on your children. Talk about them when you sit at home and when you walk along the road, when you lie down and when you get up" (Deuteronomy 6:7).