Refusing to believe Jesus is not without consequence. (John 12:48)
- He that rejecteth me, and receiveth not my words, hath one that judgeth him: the word that I have spoken, the same shall judge him in the last day.
And in the case of water baptism, scripture references that obedience to it in the name of the Lord Jesus is for remission of one's sin in accordance with Jesus' sacrifice. (Acts 2:1-39, Acts 22:16) Jesus' sacrifice made this possible for all of mankind. All have the opportunity to receive what Jesus died to provide, but not all will. For straight is the gate and narrow is the way that leads to life and
few will find it. But broad is the gate that leads to destruction and many are going that way. (Matthew 7)
Keep in mind that Jesus never said, get baptized after you are saved. He specifically stated, he that believes and is baptized shall be saved:
"...Go ye into all the world, and preach the gospel to every creature. 16
He that believeth and is baptized shall be saved; but he that believeth not shall be damned."
Obedience to water baptism is an essential part of the gospel message. (Mark 1:1-5, Acts 2:38-41, 8:12-18, 10:43-48, 19:1-7, 22:16)