How can you know what is true and then consciously live a lie? What happens to morality?

Remember that not all Christians are like that..just because a kid knows they shouldn't take that cookie out of the jar doesn't mean that they won't..we all have a conscience. We are all sinners but we can all be forgiven if we are sincerely sorry for our sins. Morally sinning is wrong. Just because everyone does it doesn't make it right though. We all have a choice to or not to sin. It doesn't mean people live a lie though. They know the truth and many try to live it but sometimes we let temptation in and sin. I don't want this to sound like I'm contradicting myself by saying that people know the truth but sin still.. In someways I guess your right with the living a lie..but at the same time it's not a lie..hope I don't confuse you and I hope this helps!