Answer
The invisible church is the church that's made up of those who are known only to God as true believers — "the elect," as we might sometimes call them — those who will be part of the visible church, but of course, those who God knows are his. And they will be regular worshipers in the kind of congregations that are made up of the visible church, but they are the ones who God knows are eternally saved.
Answer by Rev. Dr. Simon Vibert
Rev. Dr. Simon Vibert is Senior Pastor of Christ Church Virginia Water, England, and the former Vice Principal and Director of the School of Preaching at Wycliffe Hall, Oxford.