Most right-wing conservative religion?

[Bono]

Actually, Islam is communitarian/populist - they're not fiscal conservatives (ie capitalists) at all, but rather a sort of feudalist/mercantilist fusion. traditional Christianity is a bit to the left of traditional Islam - a bit more socially libertarian, and a bit more socialist in economics. Both are still communitarian/populist.

Using the true 'fiscal AND social conservative' definition, there isn't any religions that fits that criteria exactly; Orthodox/Conservative Judaism comes closest.

Christianity doesn't interfere with secular government, as oposite to islam.
Give to Ceaser what is Ceaser's...

[Bono]

I'd be inclined to say

1) Islam (in general)
2) Pentecostalist (Hardcore Evangelicals) Christians
3) Other Hardcore Christian Groups (eg Southern Baptist)

Pentecostals (not "pentecostalists"), have nothing to do with being "hardcore".Sure, most of them are, but its not because they are Pentecostal. Pentecostalism involves a certain theology of the Holy spirit, that is dubious at best, but they are far from being the most conservative group. Primitive baptists and some SBC churches would be more likely. Also some hypercalvinist Presbyterians.