Pentecostal or Protestant? Don't believe I said anything about Pentecostal and it's only one division of Pentecostal that seem to reject the Trinity. I guess you consider me Protestant and I embrace the Trinity and believe it to have existed in the OT and has always been a character of God (Deut 6:4 "Sh'ma, Yisra'el! Adonai Eloheinu, Adonai echad..."). I would also not hesitate to baptize someone who wished to profess Jesus as Lord and Savior. I invite anyone to show me scripture that prevents someone other than clergy and specific denominations to baptize. In fact, when the majority of Apostles were baptizing the nations, they were baptizing Jews, not Catholics or even gentiles. History indicates that it may have been up to 10 years before the gentiles were even invited into the synagogues to accept Jesus. Again, baptism is a symbolic cleansing event that existed in Jewish culture back to the Exodus and was done, not by a priest, but by and individual. Jews cleansed themselves in the baths outside the temple before entering. Now, to enter the Church, we must received a ritual cleaning but once to accept Jesus into our hearts, but this can be done by any believer.
This concept implies the joining of a church and not a joining of the Church. It is legalism imposed by the church, but not by scripture.