Although I totally agree with you about it relating to His person, work, and authority, both Scripture and history say it was a VERY formulaic thing.
Would you hold to that same belief of it not being formulaic if the apostles had've baptized in the Trinitarian formula? What I mean by that is, if the book of Acts had'he recorded it as in the name of Father, Son, and Holy Ghost, would you still agree that it wasn't a formula?
There is no evidence about the words that were said at baptism in the Bible. You misunderstand that to baptize into the name/person of Jesus was identification with Him vs Zeus, not magical words said in a sacramental way to cause regeneration. Many verses make repentant faith the condition of receiving grace. The verses about baptism cannot be teaching baptismal regeneration without contradiction. They do show that it was the normative, public expression of inner faith post-conversion. It is a symbolic, public, discipleship issue, not a salvation issue. Many are baptized who are not regenerated. Others are regenerated but never get baptized. You are making this legalistic when the Bible does not (cf. wrong Catholic views about transubstantiation, infant baptism, Mass, rosary, penance, etc.). When I was a pastor, I even said something like I baptize you in the name/authority of the Father, Son, Holy Spirit....in the name of Jesus. Amen. Whether the person did the ritual or not, they were already filled with the Spirit. If my assistant said one phrase, both phrases, no phrases, or in different orders, it did not matter. When I say in the name of Jesus, I do not say in the name of Jesus only. I also do not throw out Jesus' words and elevate Acts above the wording in the Great Commission. They are not contradictory for trinitarians.
You need to read Boyd's book. He deals with the heresies and legalisms of UPC from an insider perspective. God led Him to fuller understanding and freedom. You are in a sect. Like worse cultists, you do not see or appreciate the error/deception/indoctrination you are being influenced by. Those who are set free look back and see what they did not while they were in the group. My experience with UPC in my city over the years confirms that they have strong, controlling leadership, legalism, divisive spirit, misinformation about the trinity debate, zeal without knowledge. I consider them brothers in Christ, but not the heart of biblical, NT Christianity.
