I used to write a fair bit about pluralism; but have not done so recently. I continue to regard it as absolutely vital to my Christian thinking.
Yet nearly all Christians, who expressed a preference, seem to have regarded themselves as monists: that is, they assume that originally there is just 'one thing' and that is God - and every-thing that exists comes from God, and everything is, therefore, ultimately part-of-God.
This assumption creates terrible - I would say insoluble - problems of contradiction for Christians particularly; because it is vital for Christians to be able to explain evil and free will, but monism leaves no 'space' for these.
The Problem of Evil is simple and obvious. If God is everything and made everything, then he must have made evil things too; yet the Christian God is known to be wholly Good.
But where does the evil in this world come-from if God is wholly Good?
If everything is God, and God is Good - there cannot be any real evil.
Most monist Christians usually end-up asserting exactly this - that there is no real evil; that evil is just a temporary or illusory appearance of Good; and everything that is, or that happens, is ultimately Good.
However, while such a view is coherent for a Hindu or Buddhist, it is not compatible with being a Christian - where evil needs to be real.
Thus the problem of trying to be monist and Christian is the problem of trying to explain What Real Evil Is, without violating the assumption that God made/is every-thing.
In a nutshell - if you really want to be explain why evil is real - you need to be a pluralist.
The Free Will (human agency) problem is similar in form, but the problem comes from the fact that Christianity (but not all other religions) is based on love of God (and Jesus Christ); and that love must be freely chosen (or else it is not love).
Indeed each Christian must be able to choose to become a Christian; to follow Jesus by a genuine act of agency.
To put it the other way around; it is not possible (is not coherent) to be able to compel somebody to really-be a real-Christian.
So free will is essential to Christianity; which means we need to be able to explain where free will comes-from... Yet the monist has assumed that everything comes from God, and is God: everything.
Where could free will come-from if everything comes from God?
How can a total system create something like free will that is supposed to be independent of its creator?
There is no basis for free will in monism, because it is already assumed that every possible 'basis' has been made by God.
If God is everything; where is free will (to choose or reject God, to love God or not?) supposed to come-from?
Thoughtful monist Christians usually acknowledge that their metaphysical assumptions cannot explain free will; but state some version of the assertion that 'free will of Men was created by God by some mystical divine act beyond human comprehension'.
But this inability to explain free will in a monist reality is a problem, given that agency is so vital for Christians. (Not for Muslims perhaps - but for Christians, yes.)
And because monists cannot explain free will, there is a tendency to downplay free will, to ignore it; not to talk about it. Or simply to get confused about it.
At an rate, it is a chromic weakness, and indeed something of an embarrassment, that mainstream Christians are unable to give a clear and coherent explanation of free will in relation to God the creator.
The above are only two of the intractable problems that Christians encounter in being a monist; yet nearly all Christians are monists.
Intellectual Christians are, indeed, more serious about their monism than about Christianity - more concerned to maintain their monist assumptions than to be able to explain their faith clearly and simply. If any sacrifices need to be made in squaring Christianity with monism - it is Christianity that makes the sacrifices.
(In some times and places, Christianity has seemed to forget or suppress free will; and converged with pure monotheism in engaging in compelled conversion and demanding obedience to the uncomprehended will of a God, who is not 'loving' by any human discernment of love - but rather by definition (i.e. love is God, rather than God is love).)
This has been a problem since very early in the Christian Church, and has remained so.
The strange thing is that it seems likely that all humans begin as pluralists when explaining the world, and the Bible (including the Gospels) makes the easiest 'common sense' when read from a pluralist perspective. Yet nearly-all the Christian denominations and churches insist on monism as an article of faith - sustaining this ancient and intractable problem and confusion.
Mormons are the major exception - since Joseph Smith 'discovered' pluralism as a principle of Christian theology; and it was in Mormon theology, as well as the philosophy of William James, that I discovered explicit pluralism and realized it worked much better than monism in explaining those things that most need to be explained for a Christian.
Or, to put matters more accurately; the problem is monism more obviously than the solution is pluralism!
Monism is an alien philosophy wrongly-applied to Christianity; and, unsurprisingly, therefore it creates all sorts of insoluble difficulties.
However, monism will not be abandoned until there is an alternative; and almost nobody knows that there is indeed an alternative. That is the role of explicit pluralism.
Yet of those who know this alternative, extremely few bother to make the intellectual effort to understand things differently, to think them through; despite that it is so easy to do so - literally child's play!