"Is it a physical action?"
Work = Force*Distance. (I had asked where in the Bible is baptism referred to as a work.) Now, where in the Bible is baptism referred to as a sign? It is still obedience and I will leave it to God regarding the part it plays in our salvation. We are baptised "into" Christ where the blessings are. Gal 3:21-29. Are we debating when God puts our name in the book of life? Why would I (or John Calvin) try to mysticize the plain teaching He gave us.
Jesus is the sole hope for our salvation. There is no other name by which we can be save.
But, Jesus called us to ACTIVE faith.
Feed the hungry, clothe the naked, visit the sick and imprisoned, care for the orphan and the widow, give water to the thirsty, forgive, preach the Gospel, repent.
All actions and repentance and baptism are just the first steps.
All fruits of faith in Jesus, who is the vine and the producer of all good fruits.
All outward signs of faith, signs which Jesus said we will be known by others.