Why baptism? The Bible records that when persons came to put their faith in Jesus, they typically were baptized soon thereafter, often immediately. Also, Jesus specifically instructed us to baptize people in his mission to us recorded in Matthew 28:19-20
Matthew 28:19-20 (ESV) 19 Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit,20 teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age."We understand that this primarily takes place through a local church. What that means is that normally baptism involves also welcoming a person into membership in our church family. We don't just baptize people without understanding that the work of discipling and teaching will be ongoing in the local church context. There are no free agents in God's family. Who needs to be baptized? Everyone who has trusted Jesus alone for salvation as Ephesians 2:8-9 explains:
Ephesians 2:8-9 (ESV) 8 For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, 9 not a result of works, so that no one may boast.When should we be baptized? As soon as possible after trusting Jesus. Is baptism required to get into heaven? No. But is it required to make any serious progress in following Jesus? Yes. It doesn't make sense to say to Jesus, "I want to follow you with my whole life . . . well except for this first thing that you're asking me to do."