Why should I be baptized in water?

Mark 16:15-16

He said to them, "Go into all the world and preach the good news to all creation. [16] Whoever believes and is baptized will be saved, but whoever does not believe will be condemned.

Matthew 28:18-20

Then Jesus came to them and said, "All authority in heaven and on earth has been given to me. [19] Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, [20] and teaching them to obey everything I have commanded you. And surely I am with you always, to the very end of the age."

Being baptized in water is an outward sign or demonstration of something that has happened in your heart, salvation. You are showing people that you are following Jesus with your life, and you are heading down a new road. The Message translation of Romans 6 explains this pretty clearly. 

Romans 6:3-4

Or didn't you realize we packed up and left there for good? That is what happened in baptism. When we went under the water, we left the old country of sin behind; when we came up out of the water, we entered into the new country of grace—a new life in a new land!

That's what baptism into the life of Jesus means.

When we are lowered into the water, it is like the burial of Jesus; when we are raised up out of the water, it is like the resurrection of Jesus. Each of us is raised into a light-filled world by our Father so that we can see where we're going in our new grace-sovereign country.

How should I be baptized?

You may have heard that babies or young children are baptized by sprinkling water on them. These scriptures show that to follow the example of Jesus we should be baptized by being fully immersed in water.

Matthew 3:16

As soon as Jesus was baptized, he went up out of the water.

Acts 8:38

And he gave orders to stop the chariot. Then both Philip and the eunuch went down into the water and Philip baptized him.

When should I be baptized?

Acts 2:41

Those who accepted his message were baptized, and about three thousand were added to their number that day.

Acts 8:12

But when they believed Philip as he preached the good news of the kingdom of God and the name of Jesus Christ, they were baptized, both men and women. Acts 16:32-33

Then they spoke the word of the Lord to him and to all the others in his house. [33] At that hour of the night, the jailer took them and washed their wounds; then immediately he and all his family were baptized.

Water baptism should be the first step of faith you take after giving your life to Jesus. In a sense, you are crossing the line, forgetting the past, and going forward with Jesus for the rest of your life.

You should be baptized as soon as you can after you have been saved. Don't put it off. Even if you have been saved for many years and have not been baptized, you still need to obey the Lord's instruction. God will honor you when you obey Him in this area.