>>17929927
There are true things in all of them since they're all based on the observations of highly developed people (maybe not so in the case of Islam), but they're also all defined by the specific point in history at which they entered the world. For example, because Buddhism began before the resurrection, its outlook is a lot more pessimistic and centred around an eternal time loop in which humanity is stuck. Christianity, because it was established after the resurrection, which is a one way event that can't be undone, is centred around the idea of humanity's reascent towards God. Islam, because it began after the resurrection but denies the idea of ascent towards God, is perhaps the most regressive.
>why does it have to be all or nothing
A lot of people see it that way since its hard to see how two things that contradict on the surface might both be true, it requires pretty advanced thinking