I was raised Christian, and if I had to choose between Christianity and Islam, I'd probably choose Islam at least 3 or 4 times out of 10.
We forget that classical scholarship, along with universities, plus most of modern medicine and technology and mathematics, emerged from the Muslim world. And despite the prevenient emphasis on submission, Muslims managed to not be one of the religions with a silly convoluted hierarchy, and also managed to be mostly cohesive and relatively non-parochial in their sects.
Reactionary elements are not necessarily inherent to most religions, they emerge from self-seeking elements in human tendency and then sink their claws into religion to twist it into a tool to strengthen themselves.
No religion can be immune to this hijacking unless it is composed of explicitly egalitarian pillars.
Right, religions have existed before and during class society. But religions under class society get used to perpetuate class rule. Example: Christianity gets appropriated by the empire, the church becomes all powerful, Christianity becomes another instrument of repression in Europe. So really you can only purge the reactionary elements with socialist revolution.
And I don't think explicitly egalitarian religions are possible under class society. Isn't Sikhism supposed to be that, yet it fails in several regards?