If heresy on some fundamental truth is being taught from the pulpit (Gal. 1:7-9).
If the leaders of the church tolerate seriously errant doctrine from any who are given teaching authority in the fellowship (Rom. 16:17).
If the church is characterized by a wanton disregard for Scripture, such as a refusal to discipline members who are sinning blatantly (1 Cor. 5:1-7).
If unholy living is tolerated in the church (1 Cor. 5:9-11).
If the church is seriously out of step with the biblical pattern for the church (2 Thess. 3:6, 14).
If the church is marked by gross hypocrisy, giving lip service to biblical Christianity but refusing to acknowledge its true power (2 Tim. 3:5).