“But if a wicked person turns away from all the sins they have committed and keeps all my decrees and does what is just and right, that person will surely live; they will not die. 22 None of the offenses they have committed will be remembered against them. Because of the righteous things they have done, they will live. 23 Do I take any pleasure in the death of the wicked? declares the Sovereign Lord. Rather, am I not pleased when they turn from their ways and live?” (Ezekiel 18:21-23)
God requires repentance, not punishment. He wants to save us from our sins. (See Atonement, Justice and Peace by Darrin W. Snyder Belousek)
But doesn't God say he will forgive us "if" we repent? Yes he does; but there are two types of forgiveness from God.
One type of forgiveness is unconditional and the other is conditional. The unconditional kind of forgiveness simply means that he loves us unconditionally and is always doing his very best for us (see here). The other is conditional; because God will not approve of us doing things which destroy us and others. He loves us too much to ignore those things. (If you don't know that you are unconditionally loved by God watch this video.)
So even though we are forgiven, when we start to trust and obey God, he forgives us. Love keeps no record of wrongs. So how does a person trust and obey God today? They trust and obey him by trusting and obeying the Messiah whom he has sent.