What do we conclude about a person who claimed to be a Christian and then later renounces their faith and claims to follow Satan? Are they still saved?
Jesus describes the process of salvation as being "born again" in John 3 because salvation requires a spiritual rebirth. Literally speaking, our spirit must be brought back to life by the power of the Holy Spirit, and in that way, we are made spiritually new. As Paul explains:
Paul is describing being born again. Before coming to faith in Jesus, we were physically alive, but spiritually we were "dead in our trespasses" and by nature children of God's wrath. That state had to be corrected before we could receive eternal life and be welcomed into the presence of the Father. So the Spirit of God must enter our heart and cause us to be born again, which leads us to cry out to God and confess Christ, as Paul explains:
Therefore, because being born again is a work done by God in our Spirit, our salvation cannot be reversed. We cannot be "unborn" spiritually any more than we can be "unborn" physically. As Paul says:
So once a person has believed in Jesus Christ and has been born again by the Spirit, that person is forever a child of God. Paul says we are adopted into the family of God:
So then what do we conclude about a person who renounces their faith in Jesus or claims to follow the devil, etc.? Knowing it's impossible for someone born again to reverse that process, then there are the only two possibilities: either the person was never truly born again by the Spirit and has now reverted to their true nature (i.e., a child of wrath), or the person was saved and remains so though they are rebellious and disobedient and will likely receive discipline from God (see Hebrews 12).
Remember, Christians can and do disobey Christ even after being saved. Christians can even go so far as to rebel against Christ to the point of denying Him. Even the Apostle Peter denied Christ three times! Therefore, we cannot assume that egregious sin – even a denial of Christ – means a person was not saved in the beginning.
By the same token, we cannot assume that every confession of Christ is sincere. Typically, false confessors will abandon their charade after a time and renounce their "faith" – though it was a faith they never truly held in the first place.
The Lord knows who are truly His, and the judgment day will reveal it to everyone. For a complete understanding of matters related to salvation, please listen to our Romans Bible study.