Faith without works. We live under grace, not under law. Not even our best works can bring us close to Heaven.
God is absolutely perfect and the only way we will enter Heaven is through His grace. Believing in Jesus Christ as Lord and Savior.
This doesn't mean we can go around sinning. Yes ALL our sins will be forgiven, but when you give your life to the Lord, He comes and lives inside you. As we grow in Christ, our spirits have more control over our bodies and not the other way round. Our flesh is what sins naturally, so as a Christian we should strive to walk in spirit and not by sight. Focus on Jesus and He will help us turn from sin and overcome it for us.
EDIT: Like the above posters are mentioning that faith without works is dead. Someone explained this to me. If we are praying for God's will in a situation for example looking for a job or praying for salvation of a loved one we should act on our faith, on what we KNOW God will do for us. We should send out job applications, trusting God for that job, or we should buy a Bible for that friend we are praying for. Acting on our faith shows that we are serious about an answer and not just hoping for the best, we are truly trusting God for a particular outcome.