Does this seem like a suitable motto for christianity?

HUMANITY is a suitable motto for everybody !

Maybe for the spanish inquisitors and witch burnings, but for the most part that motto applies to Islam which was founded on the sword and spread by it

I think you do not understand who is a christian.

Exodus 20:13 "Thou shalt not kill."

Matthew 26:52 "Then said Jesus unto him, Put up again thy sword into his place: for all they that take the sword shall perish with the sword."

I've read that statement three times and it still doesn't make sense.

What I understood was a Christian can kill anyone that doesn't follow their religion and get away with it. I believe no one can get away with murder, we have laws and prison for that.

No. It's a straw-man misrepresentation of Christian belief (straw-man being a logical fallacy).

You mean Islam not Christianity.

Yep and muslims

"Evidence-free since AD thirty-three!"

Confess it to the pastor/jesusgod and everything is forgiven

Thou shalt not kill.