It took the Organized Church 300 years.
It took Peter one second to realize that Jesus was the Christ, the Son of the Living God.
And the Church of Christ is made up of people who realize the Truth for themselves. Upon that rock, that type of man, Jesus builds his true Church.
Which Church of Christ are you referring to in the above statement? Are you referring to the one associated with the Restoration Movement?
The doctrine of the Trinity was developed over about 300 years by the Church.
I agree with much of what you state, although the Doctrine of the Trinity is fairly commonly accepted. So much so accepted, that rejection of the Trinity casts one in the category of cult.
Instead of arguing the point, I would recommend studying the Scriptures, and make an accounting for every reference to God, and how each person of the Godhead is addressed. Let God reveal Himself to you by His Provision.