They can use passages out of context, typically old testament... do they do burnt offerings, too? One example would be Leviticus- In context, that applied to God's chosen people- in response to what they were doing after the Exodus to the promised land. The Westboro lawyer's association posing as a church is certainly not among God's chosen people.
Much of the new testament made things like animal sacrifices and "eye for an eye, tooth for a tooth" not required any more, since Christ paid for those sins with his blood. It is in the bible to show what Christ died for.
The Koran gets more and more violent towards the end, and due to Abrogation, the later passages nullify the peaceful earlier passages where they conflict.
Couple that with Taqiyya (the command that Muslims lie to infidels if it furthers the cause of Islam), and those earlier passages are left in the Koran as examples to lie to infidels when asked what Islam is about.







