Islam is the only religion TODAY that still beleives in conversion by the sword , at least that I am aware of .
As Outlaw said , I don't give a rip about the stuff that happened 600 years ago , I'm worried about the here and now....and Islam is obviously a clear and present danger TODAY .
I think you already have your secure secular state , but that won't do you a dam bit of good if the Islamists get a majority in your country , or even a stong minority .
The only important point is that Jesus never directed his followers to convert by the sword (quite the opposite, in fact), but Mohamed very clearly did. To the extent that a nominal Christian pursues that policy, therefore, he is sinning against the religion he claims to uphold. To the extent that a Muslim pursues that policy, however, he is earning his reward in heaven according to the teachings of the founder of his religion.
