One example of how one can forfeit salvation is the parable of the king who revoked his earlier pardon. A servant owed another servant a little money, but instead of forgiving him, the original creditor threw the debtor into prison. When the king found out, he canceled the debt and had the debtor tortured until he paid what he owed.
No one can deny that this parable is an obvious teaching from God. Even though He forgives those who apply for it, that forgiveness comes with conditions for the future. If we are unmerciful to others, we may lose that forgiveness. This is in line with the words of the Lord in Ezekiel 33:13: "When I tell righteous people that they will live, but then they sin, expecting their past righteousness to save them, then none of their righteous acts will be remembered. I will destroy them for their sins." The principle is repeated in verse 18, " For again I say, when righteous people turn away from their righteous behavior and turn to evil, they will die."
The secret to eternal salvation is maintaining a righteous relationship with the divine source of salvation. Jesus said, " But the one who endures to the end will be saved. " Matthew 24:13. No one will be saved ultimately who does not persist in willful sin against God's will. Those who do not endure to the end may have their names erased from the book of life. Believers who claim permanent security ignore the possibility that this could occur, but consider Revelation 3:5 for yourself--it's a sobering reality: "All who are victorious will be clothed in white. I will never erase their names from the Book of Life, but I will announce before my Father and his angels that they are mine. " The implication is clear that those who are not victorious - who do not endure to the end - will have their names blotted out.
All these verses are talking about the same thing. If someone willfully sinned, it would damage their relationship with God and they might not be able to gain eternal life. There is always an "if" in any consideration of Eternal Security because sometimes people can change. Write a new version that talks about what this "if" means for you. "But if we are living in the light, as God is in the light, then we have fellowship with each other, and the blood of Jesus, his Son, cleanses us from all sin." (1 John 1:7). "So you must remain faithful to what you have been taught from the beginning. If you do, you will remain in fellowship with the Son and with the Father. And in this fellowship we enjoy the eternal life he promised us." (1 John 2:24-25). “For in just a little while, the Coming One will come and not delay. And my righteous ones will live by faith. But I will take no pleasure in anyone who turns away.” (Hebrews 10:38). "Anyone who does not remain in me is thrown away like a useless branch and withers. Such branches are gathered into a pile to be burned." (John 15:6). "Notice how God is both kind and severe. He is severe toward those who disobeyed, but kind to you if you continue to trust in his kindness. But if you stop trusting, you also will be cut off." (Romans 11:22). "For if we are faithful to the end, trusting God just as firmly as when we first believed, we will share in all that belongs to Christ." (Hebrews 3:14). "This is a trustworthy saying: If we die with him, we will also live with him. If we endure hardship, we will reign with him. If we deny him, he will deny us. If we are unfaithful, he remains faithful, for he cannot deny who he is." (2 Timothy 2:11-13). "Dear friends, if we deliberately continue sinning after we have received knowledge of the truth, there is no longer any sacrifice that will cover these sins. There is only the terrible expectation of God’s judgment and the raging fire that will consume his enemies." (Hebrews 10:26-27). "For if you live by its dictates, you will die. But if through the power of the Spirit you put to death the deeds of your sinful nature, you will live. For all who are led by the Spirit of God are children of God." (Romans 8:13-14).