what are the philosophical proofs of Tawheed in the maturidi and a'shari schools?

I come from a Christian backround but am considering islam.truly understanding classical theistic divine simplicity led me to Tawheed,but I heard that sunni islam rejects divine simplicity so I am confused to what proofs there are in your system for Tawheed? I heard that in orthodox islam God's attributes are not identical or numerically the same as his essence(Though I heard that in the Maturidi it was but I don't think thats true,yet they deny absolute Divine simplicity),so it seems he can have posterior metaphysical parts wich make him up. why then cannot there be one essence and three 'persons' or subsisting relations like the eternalist modalists hold(catholics) or even three essences giving rise to three persons each(like Social trinitarians believe)? Am I wrong that God has parts in orthodox islamic schools like Maturidi or A'shari? if God is absolutely simple,or if he is absolutely one it would follow that he is absolutely simple wouldn't it,and then it would follow that there can be no internal subsisting relations(like the FSH modalism of the catholics) in a absolutely simple being wich would be a step towards absolute monotheism. But orthodox islam has denied this conception if I am correct? From what angle would the orthodox muslim argue against the Trinity in it's two understandings(Eternal Father-son-spirit modalism of the classical theists and the veiled Tritheism of the Social Trinitarians who reject divine simplicity like Platinga and some modern protestants)is basically what I'm asking? wouldn't a being who's essence is identical to its existance be absolutely simple?A being who's essence is not identical to it's existance is Created.the definition or synonym of a uncreated unconditioned being is a being that has its essence and existance as one and the same,yet from what I've studied this would lead to absolute Divine simplicity wich only the Imamiyah affirm? What am I getting wrong here?and from your perspective as a a'shari or maturidi what are the lists of philosophical arguments for Tawheed against multiplicity of entities as subsisting relations in one essence as the catholics hold,and there being three unique essences and three persons as the social trinitarians hold?