Two extremes are avoided. A person must not turn an assertion of faith into a declaration that all personal deeds are certainly accepted; equally, humility must not be transformed into doubt about the very existence of sincere assent.
The balanced position is to affirm present belief, hope for God's mercy, recognize shortcomings, and pray for a faithful end.
This preserves the truthfulness of the believer's current profession without pretending to possess knowledge of every hidden condition or of the final divine judgment.