Sorry, but I know several people who were baptized who not only did not believe, only got baptized for their own reasons---myself included. I had personal reasons for getting baptized, none of which had anything to do with God. Through the years, I know several people that did it for the sake of the spouse, or the children, or to get ahead in the church, or other reasons, but not because their heart was in it. When I came back to God, I was re-baptized. And as has been ststed, Jesus also said
Mat_10:22 And ye shall be hated of all men for my name's sake: but he that endureth to the end shall be saved.
Mat_24:13 But he that shall endure unto the end, the same shall be saved.
Luk_7:50 And he said to the woman, Thy faith hath saved thee; go in peace.
Luk_8:12 Those by the way side are they that hear; then cometh the devil, and taketh away the word out of their hearts, lest they should believe and be saved.
Luk_18:42 And Jesus said unto him, Receive thy sight: thy faith hath saved thee.
Joh_10:9 I am the door: by me if any man enter in, he shall be saved, and shall go in and out, and find pasture.
Jesus said be baptized once, faith and believe, much more frequently. If you can be, then certainly one should be baptized, but there have been times when a person could not be, and Jesus' baptism takes care of that----His covers it. And the Holy Spirit takes care of it---for they are baptized by the Holy Spirit.