Sorry, an Orthodox what? Jew, Russian, Greek? I don't mean to be flippant.
​Like Scouting, a lot would depend on the unit. A troop doesn't have to take anyone, but there are some adults that cannot become leaders. There is a declaration of faith involved.
​I do not see any TL restriction on youth except for age and gender, as long as they don't promote a morality that is contrary to TL or the CO. That would be backstabbing like a scout saying it is OK to lie or steal. Everyone has their own thoughts and beliefs, and they change back and forth especially when you are a youth. But you learn to "ride for the brand" while you are part of an organization, otherwise an organization just can't function.