Jesus appeared to His disciples after His resurrection.

"And he said unto them, Go ye into all the world, and preach the gospel to every creature." - Mark 16:15 KJV

"He that believeth and is baptized shall be saved; but he that believeth not shall be damned." - Mark 16:16 KJV

He that believeth what?

He that believeth the GOSPEL. (Mark 16:15).

What is the gospel?

The gospel is “that Christ died for our sins according to the scriptures; and that he was buried, and that he rose again the third day according to the scriptures.” (1 Corinthians 15:1-4).

To be saved, we not only need to believe the gospel, we must also obey the gospel. We obey the gospel by baptism.

When Peter preached the gospel on the Day of Pentecost, the people responded.

"Now when they heard this, they were pricked in their heart, and said unto Peter and to the rest of the apostles, Men and brethren, what shall we do?" - Acts 2:37 KJV

"Then Peter said unto them, 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 KJV

If we want to be saved, we must not only believe the gospel, we must also obey the gospel by baptism.

"He that believeth and is baptized shall be saved; but he that believeth not shall be damned." - Mark 16:16 KJV

(John 3:5, Romans 6:3-4, Romans 10:9-16, 2 Thessalonians 1:8, 1 Peter 4:17, Acts 8:12, John 1:12-13, Acts 10:43, Acts 16:31-33, Acts 19:4-6).