Atheists may hate religion because of wolves in sheep's clothing.
Matthew 7:15 Beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.
A lot of atheists may argue that Hitler was a Christian and so everything horrible he did, they blame Christians. Which is idiotic because he wasn't a Christian.
The bible clearly warns that people will claim to be Christian, and they aren't really. A true Jesus-Christ follower will be like Jesus in their actions.
Then atheists will say "no-true Scotsman fallacy!" But Christianity has a definition.
John 14:23 Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.
24 He that loveth me not keepeth not my sayings: and the word which ye hear is not mine, but the Father's which sent me.And by definition, given to us by Jesus, real Christians will follow Jesus's sayings, which are actually the Father's sayings, which are written to us in the bible.
Thou Shalt Not Kill was a commandment from the Lord, and obviously this means Hitler was not Christian. There are plenty of other smaller examples, such those who chant that "God hates fags" etc, they're not Christians. Jesus is all about loving thy neighbor as thy self and that's one of His commandments. You will be able to tell a Christian by their fruit.
Matthew 7:15
Beware of the false prophets, who come to you in sheep's clothing, but inwardly are ravenous wolves. 16 "You will know them by their fruits. Grapes are not gathered from thorn bushes nor figs from thistles, are they? 17 "So every good tree bears good fruit, but the bad tree bears bad fruitFor more info on Hitler not being Christian, see this video:
Hitler was a Christian DEBUNKED !!! Most Ridiculous Claim EVER!