There are some people who think the things that God did in the past are mean or cruel. We need to understand that his ways are higher then ours. Wouldn’t we be judging God if we are to think that. (Isaiah 55:9)
God is the creator so he has a right to decide what is righteous and what is sin. The scriptures tell us he is merciful,gracious and slow to anger. (Psalm 103:8) Israel knew he was merciful and when they disobeyed him they chose to have him decide the punishment instead of man. (2 Samuel 24:1-14)
There are many examples of his mercy for example when Manasseh and his people chose not to obey God he punished them. When they repented he forgave them and blessed them. (2 Chronicles 33:10,13)
We know that when he had to destroy nations or people he did not take delight in it. (Ezekiel 18:30-32)
He gave his laws to Israel, if an alien resident accepted true worship then God would view them as he did Israel. (Numbers 15:14-15) This shows he was not biased toward the gentiles. He made promises and he always keeps them. He had to do whatever he could to make sure those promises were fulfilled. So he had to protect Abraham’s bloodline. (Genesis 18:18, Deuteronomy 7:38)
God always warned people before he took action, and he held those who did not give the warning responsible. (Genesis 6:5-7, 2 Peter 2:5)(Jonah 1:2, Ezekiel 3:18)
He can read our hearts so he would know if someone was repentant or not. (1 Samuel 16:7,Luke 16:15) . We can be sure that those he destroyed had been warned and given a chance to repent.
On the other hand there are those who believe because he hasn’t acted on the wickedness going on today that he doesn’t care or that he is going to let things continue on the coarse they are going. His standards do not change. He will act just as he did in the past. We have to remember that one of his qualities is patients.(2 Peter 3:19) When it seemed like God wasn’t doing anything in the past and that wickedness seem to be prospering people would think that the wickedness wasn’t going to be punished and they would start being wicked. (Ecclesiastes 8:11)
The scriptures tells us he waited patiently for Noah to build the ark.(1 Peter 3:20) We are also told that just like in Noah’s day people would take no heed to the warnings until it was too late. (Matthew 24:38) Just as in Noah’s day he is patiently waiting for his people to finish the work he assigned now. (Matthew 24:14) If he acted without giving people a chance to repent there would be no one left because we all sin.(Romans 3:23)
Because Jehovah is a loving God he had past punishments written down to warn us so we don’t follow the same path. (1 Corinthians 10:11) A loving and righteous God could not leave the wickedness remain.
He has to destroy the wicked in our times to pave the way for the promises he made concerning the New Heaven and the New Earth. (Psalm 37:9-11:29, Isaiah 65:17, Revelation 21:3,4) He even sent his only-begotten son to show us the way, knowing what Satan and his people would do. Jesus remained loyal and faithful to the end. In doing so he defeated Satan. (John 3:16)
If you want to learn more about what the Kingdom will do go to http://wol.jw.org/en/wol/h/r1/lp-e and do a search on suffering.