Dear S.,
Presumably the Christian Church in its wisdom felt we could only sanctify Christians. That should have excluded John the Baptist. Jesus himself said that there was no greater prophet than John the Baptist, but added "he who is least in the kingdom of heaven is greater than him."
It seems to me that prophetic preaching deals with wrath (bad consequences) and earthly blessings based on what we deserve in this world. The good news of the Gospel deals with the totally unmerited love of God - however badly we perform the Father loves us anyway, the Son accepts us in His service anyway, and the Spirit is willing to empower, inspire, give gifts, etc., anyway. This is why Christian baptism is into the name of the Trinity.
John's baptism was to enroll disciples who would learn to do good and avoid wrath in this life. This is why several of Jesus disciples who had been baptized into being disciples of John, had to be baptized to become disciples of Jesus (see John 1:35-36; 4:1; Acts 19:1-7).
Admittedly there is a huge amount of John the Baptist preaching in our churches. The prophets would have preached that people who sleep around deserve the wrath of AIDS. Our task is to say that God loves us just as much when we get AIDS, and when we turn to Him we are accepted just as we are, and all the resources of the Trinity will be with us as we face our painful death. Anglican chaplains used to attend the hanging of convicted murderers, and the message was never "you deserve this," but God loves you anyway.
If we wanted to Christianize an OT saint, the best candidate would have been Abraham as argued in Romans 4. He was accepted, forgiven, and blessed in spite of being as sordid as the rest of us.
A more basic question is whether anyone should be singled out as a saint. All members of the early Christian churches were called hagioi, or saints, as in 2 Cor. 1:1; Acts 9:32. Being hagios or holy was nothing to do with spiritual success, but to the fact that we are set apart to learn from Christ by the Spirit and function as his body in the world. Paul is quite sure that some of most insignificant members are far more important than those we notice (1 Cor. 12:22-25).
Bob.