I think one of the biggest problems with modern Christianity, is we don't have the slightest clue as to how Holy and Just God really is. We are brought up being told, you want Jesus to be your friend. What happens? We treat him like a friend, like a buddy, someone you can call upon when times are tough. Don't get me wrong, Jesus wants us to be able to call upon him like a friend, but not to treat Him like one.
We need to reverence God. We need to look at Him in awe. Everything you see, and countless things you can't, He created and holds in His almighty hand. His power, His works are far from our comprehension. In the vastness of His amazing creation, we are but a speck, a tiny dot, yet he loves us with a love we can't understand. He cares so much, he gave His only begotten Son, that we would not have to endure eternal hell. Even though that is exactly what we deserve.
A God that great, that loving, that awesome, deserves our obediance. The least we can do is follow His commandments.
My advise to you is this: Make sure your kids understand God and His standard of goodness. His standard is the Ten Commandments. Keep in mind he sees lust as adultry, and hatred as murder. Also remind them of James 2:10 For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.
The need to have a bigger view of who God is. They need to understand a Christian life is one of sacrifice. It is't a bed of roses.
All that being said, I agree with Ed on the point that you need to live your faith for them to see. If you tell them all these things about the Holiness of God and how we need to reverence Him, and walk in His commandments, and then you don't. All your words will be for naught, and you will be a hypocrite that they can't believe.
Also, pray and pray some more.
Good luck and God Bless
Bill