Or you could study Scripture and see that the doctrine of 4 persons is false. Either one.
Unfortunately, the doctrine is not clearly defined in Scripture. The 3 persons are implicitly mentioned in various places, but their relationship is not explicitly spelled out. It took the Church to give final form and definition to the doctrine.
Let me ask you about this? I have a friend who "claims" to be a member of the Assemblies of God. He claims that the congregation that he attends teaches that there is no Trinity. The word is not found in the Bible, so there is no such thing. Where the Father is mentioned, that is God. The Son is Jesus, but He is not God, but a man blessed by God. The Holy Spirit is not God, but God's Grace given to man.
Would the Assemblies of God condone this teaching or would they consider it heretical? Is each individual member allowed to believe what he will concerning the Trinity or any other doctrine for that matter?
The Catholic Church sees that doctrine other than what she teaches to be dangerous to one's soul. One's wrong belief places his soul into eternal jeopardy so long as he holds the unorthodox belief.