The given quotation from Churchill means that no matter how strong the tyranny is, it can never overcome human crime.
Explanation:
The British political, military and writer, Sir Winston Leonard Spencer-Churchill was UK Prime Minister from 1940-145 when, during World War II, he led the Uk to victory.
This quote from Churchill implies no matter how strong a dictatorship is that human evil cannot be defeated and that will ultimately be undermined when the tyranny is triggered by people who want to destroy it.
The war of any of our strength and endurance which God has given to us has never been exceeded in the dark, deplorable catalog of a human criminal act to make war towards such a monstrous tyranny.