Let me ask you a question: Do you plan to do this with any other area of your children's lives? For example, do you plan to let them decide if they can play in the traffic, or eat whatever they want, or brush their teeth?
I seriously doubt it. As parents, you know you have a responsibility to keep your children from harm, and to teach them to take care of themselves. You also know you have a responsibility to teach them the difference between right and wrong; if you don't, they may end up in prison. You love your children, and because you do, you want to do what's best for them. Jesus said, "Which of you fathers, if your son asks for a fish, will give him a snake instead?" (Luke 11:11).
Why, then, would you refuse to help them discover the greatest truth anyone can ever know -- the truth that God loves them and wants to show them His will for their lives? The reason, I suspect, is because you haven't made this discovery yourselves. To put it another way, God isn't important to you, so you see no reason to teach your children about Him.
My prayer is that you will examine honestly your own need of God -- and then open your hearts and lives to Jesus Christ. Not only will He change your lives, but He'll help you become the parents God wants you to be, as you teach your children about His love -- both by your words and your example.