Well, here’s what the catholic church has to say about baptism:
“The Lord himself affirms that Baptism is necessary for salvation.” Pg. 320, #1257
“The Church does not know of any other means other than Baptism that assures entry into eternal beatitude…” Pg. 320, #1257 They also say that:
“The faithful are born anew by Baptism…” Pg. 311, #1212
“Through Baptism we are freed from sin and reborn as sons of God; we become members of Christ, and are incorporated into the Church…” Pg. 312, #1213
But the bible says that:
"But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:" John 1:12
The catholic church also says this of baptism and sins:
“Baptism not only purifies from all sins, but also makes the neophyte ‘a new creature,’ an adopted son of God, who has become a ‘partaker of the divine nature,’ member of Christ and co-heir with him, and a temple of the Holy Spirit.” Pg. 322, #1265 “By Baptism all sins are forgiven, original sin and all personal sins, as well as all punishment for sin.” Pg. 321, #1263 (See pg. 257, #985)
But the bible dissagrees:
“In whom we have redemption through his (Christ’s) blood, the forgiveness of sins…” Ephesians 1:7
Catholics try to say that baptism can be done at any time but the bible says otherwise:
“And as they went on their way, they came unto a certain water: and the eunuch said, See, here is water; what doth hinder me to be baptized? And Philip said, If thou believest with all thine heart, thou mayest. And he answered and said, I believe that Jesus Christ is the Son of God.” Acts 8:36-37
Try to find that in your catholic bible. Acts 8:37 is just a footnote. Why? Because it teachs something contrary to your churchs traditions.
All throughout scripture people believed first, then they were baptised:
"Believe on the Lord Jesus Christ, and thou shalt be saved, and thy house… And he took them the same hour of the night, and washed their stripes; and was baptized, he and all his, straightway." Acts 16:30, 31, 33
“And Crispus, the chief ruler of the synagogue, believed on the Lord with all his house; and many of the Corinthians hearing believed, and were baptized.” Acts 18:8
“… they that gladly received his word were baptized: and the same day there were added unto them about three thousand souls.” Acts 2:41
This is especially important for infant baptism. A child can’t believe yet so baptism is worthless. Baptism does not save, because Jesus said that only He saves. If baptism was neccesary for salvation He would have said so.