Yet there is a certain helpful charm in a place of prayer being the spot in which believers meet together. Also it may well be that the assemblies of believers also are attended by angelic powers, by the powers of our Lord and Savior himself, and indeed by the spirits of saints, including those already fallen asleep, certainly of those still in life, though just how is not easy to say.
And if Paul, while still wearing the body, believed that he assisted in Corinth with his spirit, we need not abandon the belief that the blessed departed in spirit also, perhaps more than one who is in the body, make their way likewise into the churches. For that reason we ought not to despise prayer in churches, recognizing that it possesses a special virtue for him who genuinely joins in.
Origen
On Prayer
Chapter XX