This is the problem with most Christians and I'm not saying that to be offensive to you.Jesus commanded, “Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit” (Matthew 28:19
Who says Peter didn't believe in the trinity?
What is weird about the trinity?
To get to the crux of the issue, the doctrine of the trinity in the first century of Jesus PBUH did not exist in its current form. In the second century it did not exist, in the third century 300 years after Jesus it did not exist.
It is in the fourth century - late fourth century when it is defined and formalized that this is the doctrine. God the father, God the son and God the holy spirit and this is one God - one being three persons. Four hundred years after Jesus PBUH it was formalized and came to existence.
You see why this concept of the trinity has zero credibility in the teachings of Jesus.
Jesus like all the previous prophets preached monotheism. God is one and worship him alone - as did Abraham, Moses and the rest of the prophets peace and blessings be upon them.
Christians blaspheme the message of Jesus, he would want zero to do with them and their heretical teachings.