If it can be argued those that turn from God were never really saved, then those that turn from Satan were never really lost? How/why can it be one way but not the other?
For one to turn from God implies he first must have been of God. One cannot turn from God if he was never of God.
Eze 3:20 "Again, when a righteous man doth turn from his righteousness, and commit iniquity, and I lay a stumblingblock before him, he shall die: because thou hast not given him warning, he shall die in his sin, and his righteous deeds which he hath done shall not be remembered; but his blood will I require at thy hand."
Also Eze 18:26-27.
Ezekiel is talking about apostates, those who have moved away from a previous standing, that is, moved from a previous standing of being righteous to being wicked and lost.
Go back to Ezekiel 3:19 Yet if thou warn the wicked, and he turn not from his wickedness, nor from his wicked way, he shall die in his iniquity; but thou hast delivered thy soul.
A righteous man of faith consist of being morally right, justifiable and virtuous. If that person turns from faith, even after someone warns them not to turn away from God then they never really knew what God's grace through faith was. Our faith is in Christ Jesus in whom we believe and trust in.
John 6:39 And this is the Father's will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day.
Gal 3:27 For as many of you as have been baptized into Christ have put on Christ.
IMO, it's not turning away from Satan, but turning away from the sin nature of the flesh that Satan uses in order to keep the lost away from the mercy and grace of God. Those who have ears to hear will hear God calling to them as He draws them to Him. Not everyone will heed His calling them.