Is it possible for a Christian to lose their salvation? No.

Is it possible for a Christian to lose their salvation? No. 

However, for the sake of having a longer post I'll elaborate on that. The idea that a genuine Christian who has had their salvation provided to them by God being able to lose that salvation is not compatible with scripture in any capacity. The Bible teaches that our Father writes the names of those to who salvation has been given into the Book of Life (Philippians 4:3, Revelation 20:15). God is not a fickle God and, therefore, will not erase these names the moment he becomes displeased at our inability to maintain a standard that could not be met in the first place.

A genuine Christian is positionally, morally perfect before God. This is solely due to the intrinsic righteousness of Jesus Christ expressed through his perfect life and keeping of the commandments. This righteousness is credited to the Christian upon their repentance and trust in the Savior. It is in no way earned and, therefore, it is in no way kept by the intent or activities of the Christian (Ephesians 2:8-9).

The bible describes all people as being spiritually dead (Ephesians 2:1, Colossians 2:13). But it also says that God determined, before he even created anything, which of these dead people he would have mercy on (Ephesians 1:4). Salvation is begun by God, maintained by God and completed by God (1 Peter 1:3-5).

A Christian can no more lose the salvation given to them as they could have willed they're receiving it in the first place. It is not based on their works (Ephesians 2:8-9) that they are saved and, therefore, works are not relevant to their becoming unsaved.

But what about people that have claimed to at one time been Christian but fell away? The bible teaches not that their salvation had been taken away and their adopted Father abandoned them. But rather that their leaving the faith is indicative of their never genuinely being of the faith to begin with.

"They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us."

1 John 2:19

It's important to understand how a Christian is called a Christian. It is not that a person decides to follow Christ and is therefore a Chrstian. But rather God decides that you will follow Christ and therefore you follow Christ and further therefore, you are a Christian. This distinction matters greatly as to how we view the subject of losing salvation.

If the choice is ours to call ourselves a Christian than the choice can be ours to stop following Christ and God can reject us. Yet if the genesis of a Christian comes from the sovereign choice of God and the maintaining of that faith comes from the enduring power of God and the purpose of the granting of that faith is for the glory of God then the matter of remaining a Christian or not is one of the integrity of God.

God will see his plan finished and will ensure his own glory. Because of this the salvation of a genuine, God-ordained Christian is as established as the reality of the existence of the Creator of the Universe.

Because of this, backsliding is not a thing. No one ever just backslides because, if you're a Christian, you're not climbing up a hill of good works and law to reach God. God plucked you from the grave, breathed life into you and set you firmly on solid ground. He indwells you with His Holy Spirit and conforms you increasingly to be more like Jesus.

An objection to the biblical understanding of eternal security is that it allows licence for a Christian to live anyway they like and to sin without thought of God. But this is not the case. Paul says in Romans:

"What shall we say then? Are we to continue in sin that grace may abound? By no means! How can we who died to sin still live in it? Do you not know that all of us who have been baptized into Christ Jesus were baptized into his death? We were buried therefore with him by baptism into death, in order that, just as Christ was raised from the dead by the glory of the Father, we too might walk in newness of life."

Romans 6:1-4

As mentioned earlier, the reality of salvation has been granted and cemented for the Christian. Yet we remain in a sinful world and, for a time, in a sin-susceptible flesh. As the Father brings the Christian through the path of sanctification there may be times where the progress is slow or we become distracted by the sides of the road. While we are guaranteed to be brought safely to our destination there may be obstacles and ditches along the way. But our Father will not leave us in our wallowing. There will always be forward progress. Even if sometimes it may not seem like it to us. But the Holy Spirit is committed to carrying us along and we can trust in his will to increasingly keep our steps sure.

There is never continuous, unrepented, willful sinning in the life of a Christian. Security of salvation does not give warrant to sin. Instead, if a Christian continues in sin willfully and does not return to God it shows that they never had him as Father to begin with. NOT that God changed his mind about keeping them.

Eternal security is an assurance and blessing for the Christian and honoring and glorifying for God. So, no, a Christian cannot lose their salvation.