Christianity Today had a column on the assurance of salvation, addressing the question of how can you know you are saved if you can’t remember the moment of your conversion. Read it here. The conclusion:
For those who question their salvation, the best evidence is not the memory of having raised a hand or prayed a prayer. Nor is it having been baptized or christened. The true test of the authentic work of God in one’s life is growth in Christ-like character, increased love for God and other people, and the fruit of the Spirit (Gal. 5:22-25; James 2:18). A memorable conversion experience may serve as an important referent to God’s saving work in one’s life. But the ongoing work of the Holy Spirit in making a person more like Jesus is the clearest indicator that one has been made a new creation in Christ.