The Search for What is Sure.

I have been interacting with a friend on what it means to be a Christian. It is amazing the conundrum such questions become when they are considered apart from covenantal thinking. My buddy is no novice; in fact he is very astute but when faced with judgments such as above he has absolutely no way to tell, objectively, who a Christian is. The discussion centers on a remark he made concerning the Roman Catholic Church. While we both agree that the Roman Church has fallen into grave theological errors (and let me restate that as very grave) he would apparently go on to say that because of their errors they are not a Christian church. While this line of thinking may at first seem to be sound when questioned it becomes obvious that it is a completely subjective statement. The question is of course where do you draw the “error line”? How grave an error can one fall into before one is considered as no longer a Christian? How do we know what God considers such an error to be? Ah, some might say, the Apostle Paul anathematizes anyone that preaches another gospel. Problem is a case could be made that when one considers what Paul calls the gospel namely the birth, death, resurrection and session of Christ the Church of Rome just squeaks by. What to do?
First of all instead of trying to decide in such cases who are not Christians we need to re-ask the question as “who is” or better yet who has put on Christ? When viewed from that (biblical) perspective the answer is simple: all those who have been baptized into Christ. Trinitarian Baptism then joins one objectively to the Covenant and is the answer to the question what does it mean to be a Christian, covenantally.