Satan merely means adversary or opponent. It is an untranslated word. Any can be a satan.
The first time SATAN is used in scripture(KJV) it is speaking of God being opposed to Israel. Compare 1Chron_21:1 and 2Sam_24:1.
Of course the 1st Christians had a Bible.
The OT is Christian scripture.
This is why the "Church" is so far from the truth of the scriptures.
To understand the NT we must know the OT.
The promises to the fathers which still have to be fulfilled.
The trinity is not in the OT and therefore not in...