The other day I came across this quote from C.S. Lewis in his book Mere Christianity:
"[Mere or essential Christianity] is more like a hall out of which doors open into several rooms. If I can bring anyone into that hall I shall have done what I attempted. But it is in the rooms, not in the hall, that there are fires and chairs and meals. . . .Even in the hall, you must begin trying to obey the rules which are common to the whole house. And above all you must be asking which door is the true one; not which pleases you best by its paint and paneling. In plain language, the question should never be: 'Do I like that kind of service?' but 'Are these doctrines true: Is holiness here? Does my conscience move me towards this? Is my reluctance to knock at this door due to my pride, or my mere taste, or my personal dislike of this particular door keeper?' When you have reached your own room, be kind to those who have chosen different doors and to those who are still in the hall. If they are wrong they need your prayers all the more; and if they are your enemies, then you are under orders to pray for them. That is one of the rules common to the whole house."