How do we know faith is essential in Christianity?

Faith is the cornerstone of the Christian life, as exemplified by the centurion in Luke 7:1-10. His remarkable belief in Jesus' authority to heal without physical presence demonstrates a profound understanding of Christ’s power. The Lord’s astonishment at the centurion’s faith shows that true faith is not dependent on signs or wonders but on a deep trust in the Word of God. The New Testament consistently affirms that faith is the means through which we receive the grace of salvation; Ephesians 2:8-9 states, 'For by grace you have been saved through faith, and that not of yourselves; it is the gift of God.' Therefore, a believer's faith is vital, as it leads to justification and sanctification.