What is a survey of Christian beliefs on those who cannot be baptized?

What do various Christian denominations believe about the requirement of baptism, and situations that impede it? For a personal example, it has been more than 3 years since I converted to Christianity; as I'm living in Iran and leaving Islam is a crime punishable with slashes and death, I tried to keep my faith hidden. There is no church where I live and a few open churches are in other cities very far from where I live and "restricted". I'm not in contact with any other Christian communities in Iran; I can't trust them. What if a Christian is not baptized? Is it a ceremony that **must** be done?