Someone who makes themself the central focus of their religion, regardless of what faith they claim to ascribe to. It is practiced by those who use religion in a self serving manner, changing the religion from its intended form to be about what they get out of it, who they can control with it, and what religion "fits them" as opposed to seeking truth, enlightenment, or what pleases their god. Subconsciously they take the god position and tailor the religion to fit them instead of changing their life to fit the religion. They do not truly worship the image or spirit of a god but their own self image or public image. Socially they present a religiously perfect image, while inside they often vastly different and continually self seeking, using the religious image to gain social status, influence, or have their egos stroked by being told how "good" they are. Most people who are Meists do not think they are Meists, but would quickly point out a few other people that they think are. Meists are the most offended at being called one, when in honesty most religious people have had to cope with some of these qualities, if not all, at one time or another in their faith.
The pharisees and sadducees that Jesus often reprimanded were Meists, as they claimed to be men of God, but used religion in a self serving manner.
A person who manipulates a holy text, through either omission or intentional forced interpretation, to excuse or condone self serving actions, would be considered a Meist.