God doesn't call the qualified, but He qualifies the called! Through the lives of Jacob from the Old Testament and Peter from the New Testament you will see that God is so good, so merciful, so gracious, that He uses flawed people and everyone is welcome in the family of God. So please don't allow a dark past to overshadow a bright future.
Romans 8:28 “And we know that all things work together for good to them that love God, to them who are the called according to his purpose.”