From History start from the Didache,
7:1 But concerning baptism, thus shall ye baptize.
7:2 Having first recited all these things, baptize {in the name of the Father and of the Son and of the Holy Spirit} in living (running) water.
7:3 But if thou hast not living water, then baptize in other water;
7:4 and if thou art not able in cold, then in warm.
7:5 But if thou hast neither, then
pour water on the head thrice in the name of the Father and of the Son and of the Holy Spirit.
7:6 But before the baptism let him that baptizeth and him that is baptized fast, and any others also who are able;
7:7 and thou shalt order him that is baptized to fast a day or two before.
expect the UPC to quote Acts 2:38 “in Jesus name”
Point out that the book of Acts was written to Theophilus, who is a pagan, roman offical
studylight.org/enc/isb/view.cgi?word=Theophilus&action=Lookup&search.x=20&search.y=12 If Luke, spoke of baptism into the name of the Father, Son and Holy Spirit to him, he would be thinking of baptism into the names of three gods. But, the great commission Matthew 28:18 was spoken to Jesus’s disciples who would understand in the name of Father, Son and Holy Spirit as ONE God by nature.
Ask your UPC freiend to explain the hebrew word elohim, it is the plural hebrew word for God. How does two become “one” echad flesh? "oh hear oh isreal our Lord God is one ( yes echad is the hebrew word. ).
Whereas, the Didache is a church manual written to Christians who would understand baptism into the name of the Father, Son and Holy Spirit as being ONE God, but three persons within that godhead.
Even as a protestant, because of whom each book was written to, in this case I think the Didache, a church manual has more authority for doctrine than an evangelistic document written to a pagan, roman official.
studylight.org/enc/isb/view.cgi?word=Theophilus&action=Lookup&search.x=20&search.y=12
The Fathers:
St. Clement of Rome, Letter to the Corinthians (C. 98 A.D.):
The Martyrdom of St. Polycarp (C. 155 - 157 A.D.):
St. Theophilus of Antioch, To Autolycus (181 A.D.):
St. Irenaeus of Lyons, Against Heresies (C. 180 A.D.):
theworkofgod.org/Library/Apologtc/R_Haddad/Course/Book1.htm#THE%20BLESSED%20TRINITY
Seek quotes from the Fathers that point out that Father, Son and Holy Spirit are seperate persons.
Home > Fathers of the Church > On the Holy Spirit (
Ambrose) > Book III
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Print out and Read Ambrose On the Holy Spirit, Book III
newadvent.org/fathers/34023.htm
He points out that a person is sent from another person, that the Holy Spirit interceedes, prays for us, Is God the father praying to himself? As seperate persons, it makes sense that one person of the Godhead prays to another person of the Godhead. But, if all three are one person, then one praying to the other makes no sense. I am pointing you to the Holy Spirit praying because they can argue that Jesus as a man was praying to God. But, the Holy Spirit is not a man.
Basically, your oneness person, is going to be using proof texts that they have been mistaught interpretations of those texts. Your position concerning the trinity is based on EXEGESIS of the scriptures which runs a lot deeper.
Read Ambrose above on the Holy Spirit, he is your best historical arguement you can put forth.
Your UPC, or oneness person will claim that his church is the orginal church based on his interpretations of scripture. Your best case is to appeal to historical church fathers which teach a purality of persons within the godhead.
Challenge them to list their complete theology, go to a computer, access the new advent site and ask them to prove that their theology is in fact taught by those whom the apostles taught.
HOLY BIBLE: Exodus 33And the** Lord spoke to Moses face to face, as a man is wont to speak to his friend.** And when he returned into the camp, his servant Josue, the son of Nun, …
The fact that God spoke to Moses face to face proves they are two persons.
But I wonder how she will take that into a black tunnel of mental gymnastics.