I know we're supposed to confess our sins to God in order to be forgiven, but I'm not sure I can remember everything I've ever done wrong. I've also probably committed sins that I didn't even know about (such as bad thoughts or motives). Does this mean God hasn't forgiven me?
No, it doesn’t—not at all. If you have truly and sincerely turned to Christ and trusted Him alone for your salvation, then you can rely on the Bible’s promise that “He forgave us all our sins” (Colossians 2:13).
This doesn’t mean we shouldn’t ask God to remind us of the sins we commit, and seek His forgiveness for them. Sin hurts our fellowship with God, and we need to be honest about our sins and ask God to cleanse us from them every day. Our salvation is secure when we come to Christ and seek His forgiveness—but we still need to be cleansed of our sins every day, so we will be pure instruments in God’s hands to do His will.
This is true especially of the so-called hidden sins—motives or thoughts that aren’t pleasing to God. Our prayer should be the same as the psalmist’s: “Surely you desire truth in the inner parts. … Create in me a pure heart, O God, and renew a steadfast spirit within me” (Psalm 51:6, 10).
Make sure of your commitment to Christ; if you have never decisively asked Him to come into your life and cleanse you of your sins, do so today. Then rejoice that He has saved you—not because you are pure or good, but simply because of His love and grace. The Bible says, “As far as the east is from the west, so far has he removed our transgressions from us” (Psalm 103:12).