What does the Bible say?

Jesus Commanded It

"And Jesus came and spake unto them, saying, 'All power is given unto Me in heaven and in earth. Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world.' " (Matthew 28:18-20)

"Jesus answered, 'Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.' " (John 3:5)

"And he said unto them, Go ye into all the world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be damned."  (Mark 16:15-16)

It Is Only For Those Who Have Believed in Jesus Christ

"Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls." (Acts 2:41, after Peter's message of Christ)

"But when they believed Philip preaching the things concerning the kingdom of God, and the name of Jesus Christ, they were baptized, both men and women." (Acts 8:12)

"Then Philip opened his mouth, and began at the same scripture, and preached unto him Jesus. And as they went on their way, they came unto a certain water: and the eunuch said, 'See, here is water; what doth hinder me to be baptized?' And Philip said, 'If thou believest with all thine heart, thou mayest.' And he answered and said, 'I believe that Jesus Christ is the Son of God.' And he commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him." (Acts 8:35-38)

"One of those listening was a woman named Lydia . . . The Lord opened her heart to respond to Paul's message. When she and the members of her household were baptized, she invited us to her home. 'If you consider me a believer in the Lord,' she said, 'come and stay at my house.' " (Acts 16:14-15)

What does Baptism mean?

God's love for you is based on what Jesus did for you on the cross and can never change. If your faith is in Christ alone, your salvation is complete in His grace and mercy. (Romans 3:22-24; 9:30-33; Ephesians 2:8-9)

However:   Baptism is a step of obedience to the One who gave His life for you, and Scripture shows it as an integral part of salvation.  According to Scripture, you cannot have one without the other - there is no middle ground.  Throughout both the Old and New Testament, we are told that those who truly believe in God are those who obey His commands.  And this commandment of baptism comes directly from Jesus, Himself.  (see Matthew 28:18-20; John 3:5; Mark 16:15-16)

In Acts 2:38, it is said that repentance and baptism are "unto the remission of sins", and in Acts 22:16, under the figure of washing, that baptism takes away sin; in Titus 3:5, that we are saved by the "washing of regeneration and the renewing of the Holy Spirit"; and in I Peter 3:21, that baptism "saves" us.  We are said to be "baptized into Christ" (Galatians 3:27; Romans 6:3) and in baptism, to "put on Christ" (Galatians 3:27); and we are told that through faith we become "sons of God" when we are "baptized into Christ" (Galatians 3:27-28).  In Romans 6:3-6 we are taught that in baptism we put off the old life and enter upon the new; and in Acts 2:38 baptism is said to be a condition of the reception of the Holy Spirit. 

On the subject of Mark 16:16, Dr. R.C.H. Lenski writes: "Both acts (belief and baptism) would precede the future act of salvation; and the meaning would be that the moment one comes to faith and baptism, salvation would be his.  . . . For one thing, faith and baptism always go together; the moment a man believes he will want and will have baptism.  By believing he clings to the gospel, and part of that gospel is baptism.  But believing is subjective, the act of baptism is objective.  They go together in this way.  Baptism cannot, therefore, be a mere sign or symbol that bestows nothing.  If it were no more it could not be so vital.