How do we know that God's mercy is sufficient for sinners?

In Luke 18:14, Jesus states that the publican, who earnestly asks for mercy, goes home justified, whereas the Pharisee, who trusted in his own righteousness, does not. This reveals that God's mercy is abundant and available to all who recognize their sinful state and seek His grace. The parable assures us that it is not our works or self-righteousness that saves us, but rather God's mercy through Christ's redemptive work on our behalf, confirming that anyone who humbles themselves to seek forgiveness will find it.