God brought down the number because of Abraham was able to plea for God’s stay of hand under certain conditions. Devout people who pray to God for His mercy can divert His Justice upon the earth.
Proof of God not evolving in the Bible: look at the Book of Revelation and you will find both the God of Justice and the God of Mercy.
God showed us compassion by sending His Son to die a horrible death so that our sins may be forgiven. God never evolved. It was because of the death and resurrection of Jesus why the change happened and the relationship between God and man and woman was restored. This does not change that God is a God of Justice and that Justice may appear to be in the form of Wrath, but it is always a Just Wrath.
The following is a private revelation, it is not necessary for an individual Catholic to accept private revelations that are approved of by the Church. However, we have “Divine Mercy Sunday” because of these private revelations. Pope John Paul II was one of the greatest advocates of this devotional.
http://www.ewtn.com/Devotionals/mercy/dmmap.htm
What I don’t like are many “Christians” who desire God’s Justice for sinners, when they must (if they are to call themselves Christians) beg for forgiveness and mercy. It is Satan who tries to bring man and woman to sin (although we do just fine without him) and it is Satan who does not want people to turn to God for mercy. He wants them to remain separated from God.
Christians must expose sin for what it is, love and pray for the sinner, that they may convert and find salvation in God. Too often “Christians” seem to take delight in the Justice of God.

IMHO, this sin is far worse than the sin of Lot’s wife. She just looked. They want to look and enjoy watching sinners suffer. I’ll imitate the women of Jerusalem during Good Friday.