We as Christians acknowledge the God’s plan of salvation at work first through Judaism in OT and then through Christianity in NT. So this question does not apply to Judaism.
This plan of salvation right from man’s fall in Genesis to the NT, is like a well oiled machine, where the OT and NT are in sync with each other. This I am saying because we accept OT in same spirit as NT and Judaism as from God because that is how God wanted to mould Jewish people to make them ready for receiving His promised Messiah. Contrary to this we find all other religions not at all compatible with each other and that applies their relation with Judaism and Christianity also.
So what would be the best viewpoint to take on these other religions? How Christians are expected to accommodate or view them vis a vis our belief. Do we have to treat them as teaching that did not have origin from God but only from human thinking or from some hallucinations?
I am looking for answers from the Christian point of view only and not from any other position of belief/unbelief.