Baptism is commanded

Sin came into the world through the very first people created and rapidly got so bad that God destroyed all the peoples of the earth except for one man and his family. 

It didn't take long after the flood before people, once again, sinned against God.

God sent His laws to His people through Moses. And He made a covenant with Abraham that if they obeyed His Law the people would have life with God.

Salvation means to be saved from eternal death that sin brings.

The Law was hard to follow and obey. People turned away often. But once a year would take an unblemished animal to the priest to be a sacrifice/atonement for their sins. The animal was killed and it was the blood of the animal poured out onto the alter that brought atonement.

Prophets spoke of a promise from God, a better way, a Messiah/Savior that would bring an end to The Law and begin a new covenant.

Jesus Christ was the fulfillment of this promise.

Jesus was literally God's Word that came in the flesh. During His time on earth he prepared followers for the New Covenant, the Way that was coming to them. He chose 12 men to teach specifically and spent three years teaching them what to do after His death. 

Jesus came to die, He is the final sacrifice required by God for sin. Through Him everyone after His death/sacrifice could have full access to God's salvation.

Every Hebrew person up to the death of Jesus only had salvation by strictly adhering to The Law of God. No other people could be saved.

Peter, one of the 12 men chosen by Jesus, preached the very first sermon on the day of Pentecost, just 50 days after Passover. He preached to thousands of Hebrew people that were in the city for the event. 

When He was done telling them about Jesus and Him being their sacrifice, many of the people were sorrowful because of the death of Jesus. They asked, "What can we do?" They wanted atonement, they were repentant.

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. For the promise is unto you, and to your children, and to all that are afar off, even as many as the Lord our God shall call. And with many other words did he testify and exhort, saying, Save yourselves from this untoward generation. (Acts 2:38-40 KJV)

Salvation now (since the death of Jesus) comes only through Jesus. He was our blood sacrifice. 

Why did Peter say in the very first sermon to be baptized? 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. 

For the removal of your sins and to receive The Holy Spirit!

Over 3000 people believed Peters sermon that day and were baptized. And scripture says, Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls. And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers. (Acts 2:41, 42 KJV) this is The Church, the group that became known as The Way and soon known as Christians.

No where in scripture is there recorded any conversions ( people being saved) without baptism being part of it. No where!

People argue that Abraham, Noah, Jacob, Moses and even the thief on the cross were never baptized and they were saved. All of these lived and died under the old covenant of the Law. Jesus had not died yet.

Baptism is not a work done by anyone to attain salvation. However it is a vital and necessary part of salvation. Just as stated in scripture,  Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life. For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection: Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin. (Romans 6:4-6 KJV)

Salvation only comes when people believe that Jesus is God's Son that came as a sacrifice for their sin. You have to believe that because there is no other way to have eternity with God than through His Son.

A person, like the first hearers of Peter's sermon, must be sorrowful and repentant of their sin and realize that it was because of their sin Jesus sacrificed His life.

A person must gladly receive the truth and not be ashamed to confess to others what Jesus has done for all.  

Then they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls. And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers. (Acts 2:41, 42 KJV)

Then be baptized. Those first 3000 believers didn't balk at being told to be baptized. They ran into the water to have their sins washed away, just as described in Paul's letter to the Romans chapter 6. They were so remorseful that they wanted/needed/ached to be changed and given freedom from the burden of their sin. 

The first century people that followed and believed got it. They knew how hard it was to live under and follow The Law. Many of them had seen or knew of Jesus. They were truly remorseful. They were heartsick in their sin. This is the part of salvation that most of us do not get or accept. 

I am so thankful, so grateful, so very very on my knees thrilled that God gives me a chance at eternity with Him. I know of the blackness of my heart without Him. I want my sins washed away. I want to die to my sin. I want to be free and cleansed. 

I will not seek an easy way. I will not seek a better way, there is no better sacrifice. I will not follow the deception of twisted scripture by those that would like to please the ears of the multitudes. 

I will pattern my life after Jesus. I will follow the church that He loved and gave His life for, the very church that began with Peter's sermon.