The thrust of this letter is: Because you are inactive in this local assembly where you are a member, we infer that you are forsaking the Church and therefore forsaking Christ who is the head of the Church. Because of your inactivity, you are being removed from the "roll."
Now, two rolls were specified in the letter: the Roll of Salvation and the Roll of Service. Neither of these rolls has any scriptural foundation that I've ever seen. The only "roll" I've seen in the Bible which would be relevant to such a discussion is the Lamb's Book of Life....in which are recorded the names of His people. It seems to me that this roll was established before the foundation of the world (Ephesian 1:4) and I don't think that refers to any church membership list.
Today's version of the New Testament church is so far removed from the model given in the epistles that it's often hard to recognize. Man has piled tradition upon tradition for the past 2000 years and made a monster. The idea of "membership" and the regulation thereof is part of the monstrosity.
The equating of salvation, being in The Church (the Body of Christ), and being on the rolls of a local assembly is a perversion of the scriptures, a high-magnitude perversion. I'm afraid this has evolved out of the man-ipulative impulses of a leadership mentality which pursues control over the lives of the membership.
The dire implications of this letter--that I am being removed from God's "roll" of some kind, something related to my standing with Him and my relationship to Christ--those implications are designed to scare me, to frighten me into obedience to the leadership. It is, in a word, blackmail.