Richard Baxter:

Whom must I judge a visible member of the church, with whom I am thus bound to hold communion?

1. If you are the pastor of the church who are made the judge, at his admission by baptism, or afterwards, you must so judge of every one who maketh a credible profession of true Christianity, that is, of his present consent to the sacramental covenant: and that profession is credible, which is, 1. Understood by him that maketh it. 2. Deliberate. 3. Voluntary. 4. Seemingly serious. 5. And is not disproved by valid evidence of the contrary. These are the true measures of church communion; for every man, next God, is the judge of his own heart; and God would have every man the chooser or refuser of his own mercies.
2. But if you are but a private member of the church, you are to judge that person a visible member of the church, whom the pastor hath taken in by baptism, and not cast out again by excommunication; except the contrary be notorious: and even then you are oft obliged for order sake to carry yourself towards him as a visible member, till he be regularly cast out.