So then you are saying your muzlim brothers worship the same 'hypostasis with the one merciful God'...
and together with us they adore the one, merciful God, mankind's judge on the last day."
It is apparent that you know nothing of Catholicism or Islam (hint, Calvinism is pretty much re-branded Islam). Islam is not a Trinitarian faith, because the Abrahamic Covenant from which it mutated is not Trinitarian.
(And for the record I really don't want to hear your polytheistic nonsense again either. As a Catholic I am a monotheist and do not acknowledge the existence or even the possibility of existence of any other God than Jehovah.)