20) How did the early Church evangelize and overthrow the Roman Empire, survive and prosper almost 350 years, without knowing for sure which books belong in the canon of Scripture?

Jesus did it, blame Him.

Matthew 28:18 And Jesus came and spake unto them, saying, All power is given unto me in heaven and in earth. 19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: 20 Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.

20) As the early Church evangelized and overthrew the Roman Empire, survived and prospered almost 350 years, without infallible pope or Magisterium and their lists of Bible books, by what law of logic are they necessary today?

I can't think of any, can you?

The Catholic Magisterium is either Superfluous or Pernicious, as it must either agree or disagree with Scripture.

If in agreement then superfluous, its product unnecessary;
if in disagreement, then pernicious, as contradicting the Word of God leads to everlasting ruin.

Since The Catholic Magisteriuim is either redundant or poisonous, nothing good comes of it.

Therefore the entity is a pointless waste of resources better spent benefiting humanity, i.e., furthering the gospel of Christ.

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The times of this ignorance God winked at; but now commandeth all men every where to repent:

Behold, I stand at the door, and knock: if any man hear my voice, and open the door, I will come in to him, and will sup with him, and he with me.-kjv