Of Saints and sinners.

In discussing character attributes it was mentioned that one of the goals of Characters in New Diasporia should be the quest to sainthood. It is not a goal every Player Character will attain to, but it is one to which some PC's should, if New Diasporia is to be different from every other space based science fiction RPG.
As was discussed every Character starts out with a level of holiness. The default starting level for any baptized character should be initially high, based upon their lifestyle. In what way do I mean? If the character is a Christian, and by design most characters will be Catholic Christians of one of the rites, East or West, then they must be what is commonly called a practical Catholic.
What is a practical Catholic? A practical Catholic is someone who follows the precepts of the particular rite of the Church to which they belong. So if they are a Roman Catholic they will abstain from meat on Fridays, attend Mass on Sundays and Holy Days of Obligation, and at least make their Easter duty of going to Reconciliation and receiving Communion. If they are members of one of the Eastern rites during Lent they will follow the strict fasting of Pure Monday and Great and Holy Friday. On Wednesday and Fridays in Lent they will keep the simple fast.
And they will adhere to the teachings of the Church on matters of faith and morals.
It is likely that in the course of their adventures that most Player Characters will fall. It is a component of the human condition and a Player will really want to have his character become a Saint to take the hard road. Becoming a martyr, when you've spent a good time building a character is not any more pleasant than the thought of real life martyrdom, though of course no where near as painful. So most characters will now and then take the easy way out.
Does that mean their quest is over? Not at all. As in real life a character can seek out a priest to receive confession.
So how is the game master ne referee ne storyteller to know where the lines are for characters? It's quite simple really. If the PC is following the authentic teaching of the Church then they are good. If they are going against it, even for good reason then they are not.
The difference between disciplines and dogma are discussing in broad terms here. Beyond that, look to the Catechism of the Catholic Church, in this matter it is your rulebook. (Don't be afraid to apply it outside the game too.)