I am sorry to be the bearer of bad news but ancient Israel was also a kingdom/empire.
You are just migrating from the conventions from empire to the conventions from another one.
If imperialism is bad there might be non-imperial calendar alternatives you may enjoy more, like the French Republican calendar.
If you dislike Ancient Rome, you may also consider not using the Latin alphabet.
Most of the atrocities you mention took place during a time when literacy rate was really low, masses took place in Latin and absolutely nobody understood what was going on. Copies of the Bible were extremely expensive and for over 1000 years there was not even paper to print them. Most of the people involved in those acts of violence had no idea what actual Christianity even meant because their only connection to Christianity was attending a church on Sunday where the entire thing was in Latin.
Jesus was an extremely tolerant guy and his message was one of tolerance and forgiveness, which is extremely unusual for a monotheistic belief system.
Another thing to take into consideration is that it is the successor of Christian imperialism mostly what helped found modern Israel and is helping protect Israel today. So perhaps it may be a good idea to relax those views a bit.