Since false teachings crept in slowly, i think you have look very early on to find the true beginning.
To drive in a wedge (metaphorically speaking) you first have to find a crack.
I think Paul provided that crack when he promoted traditions of men, customs, and his own personal opinions. (Mt 15:3, 6)
(1 Corinthians 11:2) I commend you because in all things you remember me and you are holding fast the
traditions just as
I handed them on to you. (Ga 1:14)
(1 Corinthians 11:16) However, if anyone wants to argue in favor of
some other custom, we have no other, nor do the congregations of God.
(1 Corinthians 7:25) Now concerning virgins,
I have no command from the Lord, but
I give my opinion as one who had mercy shown him by the Lord to be faithful.
(1 Corinthians 7:1, 2) Now concerning the things about which you wrote,
it is better for a man not to touch a woman;
2 but because of the prevalence of sexual immorality, let each man have his own wife and each woman have her own husband.
(1 Corinthians 7:8) Now I say to those who are unmarried and to the widows that
it is better for them if they remain as I am.
(1 Corinthians 7:38-40) So also, whoever marries does well, but whoever does not marry
will do better.
39 A wife is bound as long as her husband is alive. But if her husband should fall asleep in death, she is free to be married to whomever she wants, only in the Lord.
40 But
in my opinion,
she is happier if she remains as she is; and I certainly think I also have God’s spirit.
(1 Corinthians 7:28) But even if you did marry, you would commit no sin. And if a virgin married, such a person would commit no sin. However, those who do will have tribulation in their flesh. But
I am trying to spare you.
(1 Timothy 2:8) So
I desire that in every place the men carry on prayer, lifting up loyal hands, without anger and debates.
(1 Timothy 2:12) I do not permit a woman to teach or to exercise authority over a man, but she is to remain silent.
Paul said
:
(Philemon 8) For this very reason, though
I have great freeness of speech in connection with Christ
to order you to do what is
proper,
But Christ said
:
(Matthew 20:25-28) But Jesus called them to him and said: “You know that the rulers of the nations
lord it over them and the great men
wield authority over them.
26 This must not be the way among you;
So, no. Christ did
not give Paul the authority
"to order" anyone to believe what he thought was
"proper".
But that is what happened.
Personal opinions and beliefs not based on Christ's teachings were promoted and eventually forced on the congregation, including the Trinity.