I recently answered the question What is the Biblical evidence that there are ONLY three persons in the “Trinity?
As of right now, the question has 20 up votes that I can see. It was asked in 2011 and it's been considered an on-topic and acceptably formatted question for about five years.
The question asks:
What is the Biblical evidence, if any, that there are only three persons in the Godhead? Perhaps there are others that are not revealed specifically through scripture, or perhaps we attribute multiple "persons" to a single concept of Father or Holy Spirit?
I was under the impression that "evidence" meant "What have trinitarians considered the available body of facts or information indicating whether a belief or proposition of the trinity is true or valid?" (I copied this definition of evidence from Google, and I don't think there is any reason why it's insufficient). So although the OP knows the trinity doctrine isn't "specifically spelled out in Scripture", they are simply asking for evidence that indicates there are only three persons of the "godhead".
The OP also mentioned that perhaps there are other persons not specifically revealed, to which I included a very common trinitarian argument and applied this argument to other verses with similar language- to show why other persons could technically be added to this "godhead".
The part that really drew my attention to this question was "if any". I understood this to mean if there is any evidence, the OP would like to know; but if there isn't any evidence, they would also like to know so that they don't continue to assume there is.
I don't really care if my answer remains deleted, but I'm wondering what I did wrong so that I don't make the mistake again. I provided every verse that I could find that mentions the words father, son, and spirit, which have all been provided to me as evidence of a triune god, but I explained why I disagree.
I consider myself to have as much comprehension of the trinity as one can have of something that is explicitly stated as incomprehensible. I did say one thing that I know is not correct according to the trinity doctrine:
If I'm not mistaken, according to trinitarianism, this next verse says that God is sitting by the right hand of God and God has received from God the spirit of God who is also God. So all three gods are also present here:
"Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he [Yeshua] hath shed forth this, which ye now see and hear." Acts 2:33
The first sentence I'm sure is correct according to trinitarianism. For the second sentence, I understand that the correct term would have been "persons", but I counted three entities called God so I felt it was appropriate. While it's not correct according to the formula, I do believe it's correct according to arithmetic.
My conclusion says:
Nothing in the bible explicitly says there are only three persons within the "godhead" because nothing in the bible says anything about three persons or a triune god.
I gave this conclusion to answer the "if any" part of the question. I don't see any evidence that the "godhead" should only contain three persons, and I cannot find any commentaries or studies that give reasons why the "godhead" should be limited to three, so I concluded there are none.
Could somebody please explain what I did wrong so I can fix it and provide better answers in the future? Thank you.