Where does that leave the Satan Theory?
Seems to be a lot of confusion and some very muddled doctrines in your OP.
1. I have never known of a water baptism ceremony that you describe.
New converts confess their faith in Jesus as their Lord and God and their Saviour. They are asked if they
believe that Jesus died for them for the remission of their sins and that he rose from death to give them
new life in him. Words to that effect. Confessing the gospel of salvation.
Satan, along with other fallen angels or demonic beings, is virtually absent.
Perhaps you should actually read the Bible for your truth and information.
My copy of Nave's Topical Bible (1979 ed) page 1238 SATAN has several pages of scriptures under this heading. There are many many verses pertaing to Lucifer, Satan, serpent, Morning Star, dragon, the devil, demons, adversary, evil one, murderer, liar ...
Even Jesus himself spoke of Satan directly: John 8:44
There are no shortages of scriptures directly referring to Satan, demons and the Devil.
"Set thou a wicked man over him: and let Satan stand at his right hand."
Psalm 109:6
Also look up in your Nave's Topical Bible the subject headings for SIN and for EVIL.
Again you will see how these verses also embrace the concept of Satan, rebellion and self-will.
36 Neither can they die any more: for they are equal unto the angels; and are the children of God, being the children of the resurrection.
Angels are eternal. And we as believers and disciples of Jesus have faith in our future immortality
when we are transformed from flesh to angelic beings.
So obviously if angels do not die then Satan and his fallen brethren (demons, etc.) have existed since
the beginning from when they were created by God.
That is why in the end Satan will be condemned to an eternal place of damnation - because spiritual
beings do not die in the sense that we mere mortals know of death...
"And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and
the false prophet are, and shall be tormented day and night for ever and ever.
Revelation 20:10