Language often makes things difficult.
First, we must realize that God is unique. I would hope we could agree on that?
But the way language works is that a word is minted to describe something and then it changes over time depending on usage and such.
God would be such a word in English. It’s origin is in pagan gods, not the one true God. Allah would be similar.
When we discuss the Trinity, it is very difficult because we take words, not unique to God, and try to describe the unique God.
God is one, there is one God. This is actually an agreement between Muslims and Christians. Anyone who says differently is guilty of misunderstanding, or they are taking some group that says they are Christian who really don’t hold to the fundamentals of the faith.
God is one. One must keep that in mind throughout the discussion of the Trinity. If, at any time, you think something said conflicts with that, well you are taking the wrong understanding.
Three persons is often misunderstood as three gods, or three beings. That is wrong. God is one. Often people take the word person to mean separate distinct beings. That’s easy to do, most of the time like with human beings, that would be correct. But that isn’t really the meaning of the word.
In order to try and explain God, a word was taken from the Roman theater. Persona. Now understanding it’s roots helps understand the concept. Note that when three persons was first used, the Roman theater was actually in existance and it’s meaning would have been evident in a way that is not true today.
The persona was the mask the actor wore. You knew which character he was playing at the moment by the mask, the persona. It was common for an actor to play more than one part at a time, even have conversations with himself. He would simply hold up one mask and say something, then another mask and respond to what he just said and go back and forth.
So that is how an actor could have multiple personas.
God has three personas, the Father, the Son and the Holy Spirit, God is one!
The major difference and the error that has been relatively common is to fall into modalism. Thinking God is like that human actor in wearing one mask and then another but always one at a time. That is a mistaken idea. God is all three personas at the same time, God is one.
Or falling into the error the Muslims suffer from of thinking three personas equals three gods. Groups such as Mormons, who call themselves Christians do make the error of separating the Father from the Son.
Mohammed was at a disadvantage. If you had told him to read the Bible verses to gain understanding, well he couldn’t do it, Mohammed could not read. So he relied on what he heard from others. If you read the Quran carefully, it does appear that the Trinity he is complaining about is not the Christian Trinity. It appears that he was influenced by a Marian cult and likely was complaining of people who worshipped the Father, the Son and the Mother, Mary. This was common in that part of the world at that time. A grevious error, idolatry, and certainly a mistake that should be condemned. Notice he complains more than once about the Mother and her Son and the worship of them. But also notice he never complains about the Holy Spirit though the Holy Spirit is mentioned.
It is unfortunate that Mohammed could not read and study the Bible. If he could have spoken more of it instead of second hand misunderstandings that became deeply ingrained.
who are you addressing this to?