The Muslims have yet to renounce slavery. How can they renounce war?

Muhammad was a slave owner, as was George Washington. But unlike other religions and atheists, the muslims have yet to renounce slavery. Even the most successful of present day muslims will tell you that he would happily trade his 21st century life to live as one of Muhammad’s slaves. In other words, being a slave is a good thing just so long as you have a good master and a great thing if you are owned by a great master. Unlike Americans, muslims are in no way embarrassed by their legacy of slavery. On the contrary, they see it as an integral part of their golden age.

But here is my question. If slavery is a desirable state of being why not war as well? If the buying and selling of humans is legitimate why not wars of conquest? How can one thing be good and the other bad? How can people living in the modern era consider a slave owner to be the most morally sound human ever to live?