all religions are not the same, and they do not come close to describing the same God/pathways etc.
i agree, if by Christianity you mean the common ideas as they are interpreted and understood by
most, but it is always subjective what one means when he uses such words like Christianity or heaven or death.
for me, a religion is not defined by its scripture, but by the sum of
all interpretations of those, who are interested in the topic
if you assume that someone somehow understands mysticism, he must focus on the common aspects, because there is only one possible range of experiences of enlightenment (and all religions are originally inspired by possible experiences). so Christian ideas like trinity must be assumed to be perspectives of a more relative, subtle stage or stage, than brahman, for instance.
incompatibility can only exist in language statements that are removed from their source or experience by subjective interpretation and hearsay. if you know how to interpret the ideas for what they really (originally) are, then you can put them on a single map. samsara and bardo have all the potential that is needed to host experiences of apparently eternal (timeless) hell, heaven, virgin doll house, jesus, other deities.
the biggest difference may be the idea of reincarnation, but what this word means is also subjective, it may well be compatible with both atheistic death and ideas of joining ancestors in heaven.