I am a pluralist Christian; because I believe that we need pluralism to break the (often) tyranny, the false implications, of the absolute and crushing grip of monist monotheism.
Accepting, as I do, that neither monism nor pluralism is a complete and fully-coherent metaphysical description of ultimate reality - I assert that, despite its historical rarity, pluralism is better for Christians (although not for the other major monotheisms).
None of this is to challenge the truth that there is, for Christians, One God. But One God does not, according to scripture and by common-sense, imply philosophical monism.
Monism is a philosophical theory that predates Christianity - and which states that everything ultimate reduces to one thing - in Christian terms that God is one entity that is/ contains everything else.
It has always been extremely difficult (I would say impossible) for Christians satisfactorily to accommodate the primary and essential reality of Jesus Christ within monism in a manner which is comprehensible or meaningful.
The only widely acceptable answer has been to declare the whole thing a mystery, expressible only in self-contradictory/ paradoxical language (e. the mainstream dogmatic linguistic formulations regarding the Trinity). But in terms of philosophy or common-sense this is no answer at all, but an evasion positioned at the very heart of Christianity.
The fundamental distinction is that pluralism is anything more-than monism; the fundamental distinction is between One and More-Than-One.
The precise numeration of how-many more-than-one is secondary, and a subject for revelation rather than philosophy.
In other words, we cannot known how many more than one by reason alone - such knowledge must be told us, must come to us, from divine sources.
General Christian revelation tells us that more-then-one includes primarily and minimally Jesus Christ; also, but in a different sense, the Holy Ghost; Mormon revelation adds our Mother in Heaven.
These are minimally and essentially necessary to complete the basic picture; but in fact they do not complete the picture; because the picture includes all the Men and Angels who ever lived. All personages bring to reality something significant and permanent - albeit not-essential to its existence.
For a pluralist Christian there is One God, meaning that our Heavenly Father is primary as creator and legitimate authority - but also God needed, and continues to need (and always will need), others to do his primary work.
Since we are not monists, there is no requirement to reduce a multiplicity to one. Indeed, more-than-one implies irreducible and necessary qualities as the basis of difference between personages.
Pluralism makes clear why the Good Shepherd cares about all his flock, each and every individual; because each is unique and by his or her nature unique. Take one away, and the universe is changed; and changed for the worse from the perspective of the Good Shepherd - who will forever grieve the loss.
The greatest temptation is therefore to choose damnation as a sure way of hurting God - the power to do this is real and intoxicating for those not bound by Love.
The power to hurt God is real in a pluralist universe but it is nonetheless a snare; because while every act is permanent and irreversible, and by it the universe is changed; nonetheless overall progression has merely been delayed and not stopped.
Over eternity, and with spiritual growth of multiple personages, there are unbounded possibilities for Goods - there is not a single 'perfect' Good which can be marred, but an open-ended number of Goods all of which are capable of further enhancement and which can be achieved in uncountable ways.
Note added: This is related to the necessity for divine revelation.
Revelation is required precisely because metaphysics (i.e. the structure and history of ultimate reality) is contingent. It could have been different, and its future is undetermined in detail (although not in direction) due to the multitude of choices by a multitude of relevant personages.
Therefore reality cannot be inferred by philosophy, from reason.
The primacy of revelation itself implies pluralism as the best metaphysics for Christians; because pluralism allows for contingency in a way ruled-out by monism.