Peter talks about Baptism, but there are many different views of Baptism and types. Full immersion Baptism is just one view. Many passages in the New Testament talk about Baptism of the spirit, etc.

Sprinkling baptism was just a tradition they made up who knows how long ago along with alot of the other things they perform in church during mass, for ex. for those who didnt know that when you recieve communion you are supposed to believe in you heart that you truley deserve it and you should only accept it if you feel your living your life completely for god doing everything you should be(which means if you were just sleeping with your boyfrind the night before wich is a sin you should not be getting communion!)and a lot of ppl still do and its it the bible that you are actually cursing yourself..

The Catholic Church teaches: Baptism is performed in the most expressive way by triple immersion in the baptismal water. However, from ancient times it has also been able to be conferred by pouring the water three times over the candidate's head. (Pouring is a bit different from sprinkling.) In accordance to the command of Jesus Christ in Matthew 28:19-20: "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, teaching them to observe all that I have commanded you." Catholics baptize using the words, "[Name], I baptize you in the name of the Father, and of the Son, and of the Holy Spirit." The Catholic Church accepts any baptism from other Christian Church if it was done in this manner. It has been argued by people smarter than me that not only was there not enough fresh water to baptize three thousand people in Jerusalem but there would not have been enough time to baptize all of them by full immersion in one day even if they started in the morning. Could these have been baptized by pouring water over them? For more information, see the Catechism of the Catholic Church, section 1239: http://www.usccb.org/catechism/text/pt2sect2.htm#1239 With love in Christ.