They said therefore to him, "What must we do, that we may work the works of God?"
What must we do ... ? means "What must we do to be saved?" and is a question encountered several times in the New Testament.  On Pentecost, in the jail at Philippi, and on the Damascus road, the question "What shall I do?" was the initial movement of souls toward the Lord.  The question has a Scriptural answer, and it is criminal to substitute the sophistry of men for the divine answer.  In answer to this question, the Holy Spirit said: "Believe on the Lord Jesus and thou shalt be saved ...  Repent and be baptized every one of you in the name of Jesus Christ unto the remission of your sins ...  Arise and be baptized and wash away your sins calling on his name" (Acts 16:31; 2:38; 22:16).