“If you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved” (Romans 10:9). Seems simple enough. So simple in fact that some non-Catholic Christian assemblies base their “once saved, always saved” doctrine on this type of statement. In effect, they say that because of this one time confession a person can’t loose their salvation no matter what they do, as long as they’ve sincerely made the commitment to Jesus. However, this presumption or “absolute assurance of salvation” doctrine contradicts New Testament teaching.
In Romans 11:21-22 St. Paul addresses the sincere believing Gentile converts and indicates that they could be cut off if they don’t remain faithful. In his letter to the sincere believing Corinthians he indicates how he trains himself so as not to be disqualified (1 Cor. 9:27), and then tells the believers that “whoever thinks he is standing secure should take care not to fall” (1 Cor. 10:12). Hebrews 6:4-6 and 10:26-27 discuss the punishment for those who are true believers and then have fallen away.
Jesus tells us two different times (Matt. 10:22 and 24:13) that we must persevere to the end in order to be saved. The OT foreshadowing of these NT teachings is found in Ezekiel chapter 33, particularly verse 13: “Though I say to the virtuous man that he shall surely live, if he presumes on his virtue and does wrong, none of his virtuous deeds shall be remembered; because of the wrong he has done, he shall die.” Thus according to God’s Word, the presumption of “once saved, always saved” can be fatal!
It is because of our weakened free will that we have no absolute assurance of salvation. Our faith, however, does provide us with a confident assurance of that which we hope for, knowing that as long as we continue in God’s graces, He is true to His promises (Hebrews 10:23). It is this hope of salvation spoken of many times in Scripture, which continues to be faithfully taught by the Catholic Church. (Ref. Catechism paragraphs 1817 to 1821).