The last sentence "There is no need for a Third Person of a Trinity" is a clear non-Christian statement.
Remember, your interpretation imposed onto Scripture is not the infallible Word of God, neither is the interpretations of the man you chose as your teacher, Richard T. Ritenbaugh, infallible as he was not sent by God. The Bereans started about 100 years ago, they don't know the teachings that the Apostles received from Jesus. Teaching has to be passed down from Apostles to faithful men who would be able to teach others (2 Tim. 2:1-2).
The Christian is baptized in the name of the Trinity: “in the name of the Father, and of the Son, and of the Holy Spirit” (Matt 28:19)
Ad hominem.
https://www.bibleportal.com/sermon/Keith-Malcomson/the-triunity-of-god Your favorite preacher believes in the Trinity, why don't you?
"But in I John 5:7 we are told, “there are three that bear record in heaven, the Father, the Word and the Holy Ghost; these three are one.” By this we see that there is no contradiction in calling the Father, the Word and the Holy Ghost one as well as three. God is just as much three as He is one."