How do we know faith is a good work according to the Bible?

The Gospel of John emphasizes that Mary's act of anointing Jesus was not merely about the physical act itself but was deeply rooted in her faith. Jesus indicated that she had preserved this act for his burial, highlighting her understanding of his impending sacrifice. In the same way, faith is regarded as a good work because it acknowledges and accepts the grace and salvation offered through Christ's death. It is not a work of our own merit but is credited to us as righteousness when truly believed. This transformation—wherein God gives us the gift of faith—demonstrates that true works pleasing to God begin with a heart that believes on His Son.