What does the phrase 'I do not frustrate the grace of God' mean?

In Galatians 2:21, Paul emphasizes that to mix grace with works is to frustrate God's grace. He insists that salvation must be entirely by grace through faith and not based on human merit. The false belief that one can earn salvation undermines the necessity of Christ's death, effectively making grace a lesser aspect of salvation. Thus, to uphold the integrity of the gospel, believers must recognize grace as the primary means of salvation without the inclusion of works as a contributing factor.