In determining the correctness of a church, the matter of condition is secondary; the primary matter is the ground [1 Corinthians 1:2, 11-13]. Sadly, people’s knowledge of the church is mainly based on the condition of the church, and they neglect the ground of the church. When speaking concerning a certain Christian group, they feel that there is no problem if the people are zealous, holy, and spiritual. This is to know the church based on condition, not on the ground. This is dangerous.
Condition is relative, but the ground is absolute. …Moreover, conditions may change. Someone may not love the Lord today, but perhaps tomorrow he will love the Lord very much. A particular group may not be spiritual today, but next year they will become very spiritual. Therefore, the assessment of a church can never be based on its spiritual condition but on its ground. Its ground is absolute and can never change. (Lessons for New Believers, ch. 16, by Witness Lee)
Read more via, The Ground of the Church.