Remission of sin requires to believe that our sins can be forgiven.
There are people around us who live a bittered life, blaming themselves, in constant fear and sadness, because they don't believe they can be forgiven (ie, spiritually healed).
When Jesus healed people, He required them to believe... but to believe what?
In his preexistence, atonement, resurrection, Second Coming? In Sola Scriptura, baptism, Sunday keeping, the Holy Spirit?
No.
They needed to believe that, if they were blind, they could see again. If they were crippled, they could walk again. If they were afraid or hated or dead inside, they could find peace, and love, and eternal life.
This is the faith the Gospel is all about.