37 Now when they heard this they were cut to the heart, and said to Peter and the rest of the apostles, “Brothers, what shall we do?” 38 And Peter said to them, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit. (Acts 2:37-38 ESV)
In a devotional I read this morning it talked about the two things necessary for salvation; belief and repentance.
God does not expect us to come to Him with our life totally cleaned up. He realizes that there may be a lot of cleanup (repentance) needed on the isles of our store. However, there does need to be true repentance and that needs to be a continual work in our lives.
This is more than being sorry for what we did before we believed, but a true and complete turning from our old sinful ways. Repentance is needed throughout our lives as we will backslide and we will have moments of weakness. This is the human condition. This is not an excuse to sin, but an acceptance and understanding of our weakness.
As we consider our lives as new believers or people mature in the faith, we must consider have we only accepted forgiveness or have we truly repented. If we are holding out a piece of our old life we must completely eradicate these behaviors and ask God to give us strength. Beyond this, just believe and surrender.