Credo in unum Deum, Patrem omnipotentem, factorem caeli et terrae, visibilium om-nium et invisibilium.
It's the same sort of thing.
After all the creed goes on to say "and in JC his only son, begotten, not made, of one being with the father... and in the holy spirit..."
Back when I was a religious believer, my vicar (spendidly liberal Christian) used to joke that most sane clergy timed their holiday to coincide with Trinity Sunday so some other bugger had to preach about the trinity.
Believing several impossible things before breakfast isn't just an accidental part of religions/quasi religions, it's actually central to them.
It's a way whereby the faithful can demonstrate, very visibly and publicly, that they are so devout and virtuous they are prepared to put all other things - family, friends, material wealth, even logic and the evidence of their own eyes - to one side to demonstrate how holy they are.