“He that believeth and is baptized shall be saved” (Mark 16:16).
The twelve apostles preached and practiced exactly this. When Peter’s hearers at Pentecost were convicted of their sins and asked: “Men and brethren, what shall we do” Peter did not tell them that Christ had died for their sins and that they could receive salvation as the gift of God’s grace, apart from religion or works. Rather he said:
“Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost” (Acts 2:38).
Years ago, in a series of debates on dispensationalism, the author asked his opponent: “Suppose, after a Sunday evening service, some of your hearers were convicted of their sins and asked you and your co-workers: ‘Men and brethren, what shall we do?’ Would you tell them what Peter told his convicted sinners at Pentecost?”
“Why, of course!” he exclaimed.
“In those words?” I persisted.
He thought for a moment and then replied: “Well, I guess not exactly in those words.”
The fact is that this pastor would not at all have said to his hearers what Peter said to his. Even though a Baptist, he would not have said: “Repent and be baptized every one of you in the name of Jesus Christ, for the remission of sins,” for he believed that subjection to water baptism should be left to each person’s conscience, and he did not believe that it had anything to do with salvation. He would doubtless have said to any inquirers what Paul said when the convicted Gentile jailor asked: “What must I do to be saved?” Like Paul, he would have replied: “Believe on the Lord Jesus Christ and thou shalt be saved.. .” (Acts 16:31). Peter at Pentecost preached what he was commanded to preach under his commission: “He that believeth and is baptized shall be saved” (Mark 16:16), but when God raised up Paul, that other apostle, He sent him to proclaim “the gospel of the grace of God” (Acts 20:24) and the finished work of Christ. source