John the Baptist

  11“As for me, I baptize you with water for repentance, but He who is coming after me is mightier than I, and I am not fit to remove His sandals; He will baptize you with the Holy Spirit and fire.12“His winnowing fork is in His hand, and He will thoroughly clear His threshing floor; and He will gather His wheat into the barn, but He will burn up the chaff with unquenchable fire.”

At that time John was baptising people and he was preaching to the people, including the Pharisees and Sadducees. He told the people that although he baptize people with water, he prophesies that there would be a Man who will baptize all man with the holy spirit and fire.
 
Well, we should know what is the significance of baptism. 

Baptism is defined as:

1. (Christianity / Ecclesiastical Terms) a Christian religious rite consisting of immersion in or sprinkling with water as a sign that the subject is cleansed from sin and constituted as a member of the Church

2. (Christianity / Ecclesiastical Terms) the act of baptizing or of undergoing baptism

3. (Christianity / Ecclesiastical Terms) any similar experience of initiation, regeneration, or dedication

 

Note the first definition; the subject is cleansed from sin and constituted as a member of the Church. Means its an act of declaration, declaring that one is part of the church. 

The last one is experience of initiation, regeneration or dedication.

initiation: formal declaration of entry

regeneration: renew

dedication: formal declaration of fellowship

So, we see that Baptism is very significant, you die and rise again with Jesus. Its a physical ceremony to mark that day that you officially come to Christ, as opposed to saying the sinner's prayer.

Then there is the baptism with the Holy Spirit. It is the act of receiving spiritual gifts through Jesus Christ!