doesn't Christianity say that all non-believers will burn in hell for all eternity. I mean, if you believe that to be literally true then a death sentence on top doesn't actually seem a whole lot worse.
That statement is ridiculous sir. To say that someone who believes you are going to hell for leaving a religion is the same as the constitution of islamic countries that say BY LAW apostates MUST be killed is....well it's obvious. 
So someone thinking I'm going to hell is as bad as actually killing people huh ? care to explain that ? It's a lot different to the person who is going to be killed I'm sure !! give me the choice of living knowing christians think I'm going to burn in hell or being killed by muslims, I know which choice I would take.
all in all, you are opposed to all the right things, radicalism, religious imperialism, sharia law (which is horrific). I'm just trying to say that it is wildly inaccurate to say that all Muslim's subscribe to these things. indeed, there are those in almost every faith who have similar beliefs.
Not all muslim's will cut off an unbelievers head, but the majority of them will sympathize with the cutter not the cutee. Proven time and time again by riots for koran burning but none in the streets for killing infedels.
for example, the inquistion of the vatican still exists as an institution, they just changed the name in the 60's. they spent over a thousand years banning books and punishing, torturing, killing and waging war against non-catholics, amongst other things. is this not a huge threat to western societal freedom? of course it is. but general ignorance leads people to forget about it. and in just the same way as in Islam, the vast majority of catholics would never condone and are actually against such actions.
Lol The inquisition..... still killing ? get real.
I'm sure 99% of Christians would be horrified and offended if i was to lump them into the same group and belief system as the westboro baptist church. of course, most are not, that's a ridiculous thing to say, but it is a generalisation not that dissimilar to those you are making.