The parable in Matthew 18:23-35 illustrates the big picture of how God forgives us of an unpayable debt. It then demonstrates the absurdity of how one who has been given such grace can then withhold forgiveness of a much smaller debt, as though the gift meant nothing. Jesus appears to be reiterating a teaching that He stated prior in the book of Matthew. “For if ye forgive men their trespasses, your heavenly Father will also forgive you: But if ye forgive not men their trespasses, neither will your Father forgive your trespasses” (Matthew 6:14-15).
God’s gift of His only Son to pay our debt and grant us forgiveness should have a changing effect on our hearts (Ephesians 4:32), which is what God is asking for in the parable, “So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother their trespasses” (Matthew 18:35).
While God is explicit in His directive to forgive, the parable also teaches that we must first experience the forgiveness of God in order to be able to forgive others. We cannot forgive in our own strength and may need to pray for God to help us forgive, but that is a prayer God will hear (Mark 11:25). It may be difficult, but as Jesus forgave those who crucified Him (Luke 23:34) so can we forgive others with His help when we are tempted to hold a grudge (Hebrews 2:18).
The Bible states that there are books in heaven and that those who are saved are written in the Book of Life (Philippians 4:3, Revelation 20:15). Jesus tells His believers that if they overcome known sins that they will not be blotted out of this book (Revelation 3:5). It would then stand true that if they did not overcome those known sins, then they would be blotted out of the Book of Life. If we know better than to hold onto a sin, yet do it willingly, we cannot expect to stay forgiven (Hebrews 10:26-27).
The Bible speaks of people who were once God’s servants but later fell away, such as king Saul (1 Samuel 1:10-11, 1 Chronicles 10:13). It states that people will depart from the faith (1 Timothy 4:1). This is also seen in the parable of the sower (Luke 8:5-15) where some fall away (vs 13). This is why Jesus says we must abide in Him (John 15:4-6). Those who endure to the end are saved (Matthew 24:13).
We can have assurance of our salvation and can trust that God is faithful to save us if we remain standing in the gospel (1 Corinthians 15:1-2). While no one can pluck us from Jesus’ hand (John 10:28-29), we ourselves can choose to leave. This freedom of choice comes from a God of love (1 John 4:8) and He respects our decision to accept or reject Him. God is very clear that He only desires that we be saved(Ezekiel 18:31-32) and we can know we are saved as we remain in connection and obedience to Him (1 John 3:2-5). We may make mistakes, but we are safe as we keep getting back up and looking to God for forgiveness and help (Proverbs 24:16, 1 John 1:9, 1 John 2:1).
So, then if a believer refuses to forgive, which disobeys a direct command from God, it is clear from Scripture that they would indeed lose their salvation. “When a righteous man turneth away from his righteousness, and committeth iniquity, and dieth in them; for his iniquity that he hath done shall he die (Ezekiel 18:26). While God desires for everyone to come to heaven, He will not allow anything there that will defile it (Revelation 21:27). Any evil in the heart defiles (Matthew 15:18) and heaven is a place of healing and peace (Revelation 22:2). Unforgiveness has no place there.
In His service,