Yes, a grotesque 3 headed monster God is laughable.
Then again, the Hebrew scriptures explicitly indicate that God is more than a singular entity.
Every time that the OT references the 'oneness' of God, it is with the plural one. I know, you're thinking 'Hey, The Truth Will Set You Free, what are you talking about? You make no sense at all. How can there be a plural one?'
In Hebrew there are 2 words for one. There is the singular one and there is a plural one. Yachid and Echad.
The singular one is self explanatory, the plural one is the combination of things to create 'one'. You could say that a congregation is a plural one as all members of the congregation make up a plural one.
Direct scriptural examples include references to 'man and women became one [plural one] flesh' 'night and day became one [plural one] day' and 'hear o Israel that the Lord your God is one [plural one] God'
So, in the Hebrew scriptures is explicit evidence of the plurality of God. If we look at IS 9;6 we see that Jesus IS God, so how could he be God as a child and still have a God running the universe?
For to us a child is born, to us a son is given, and the government will be on his shoulders. And he will be called Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace.
Answer- One [plural] God
Not explaining the mystery of the Trinity, just stating that the scriptures agree with the possibility of the concept.