I would like to offer a comment on this aspect of your thoughts if I may
IMHO There is indeed one God and one Purpose and God does not have to be Morally wrong for it to be so.
The greatest understanding we can have about God is that He does as He wills!
This is the most great bounty to us, to which is a very different subject that would take away from this thread.
To find the One God in all the Great Religions could be one easy step, that is to look with the eye of oneness.
In all the scriptures of all the religions where we may see no evidence of unity, we might only have to slightly change our mindset and a new meaning can tie them all together.
It could be as simple as Man not quite getting the meaning of scripture right! Gods purpose never changes, His Love for us, that is every person, is always there
Why then do we try to separate and use God exclusively just because we think scripture says so?
Well worth the thought - God bless - Regards Tony