St. Silouan the Athonite: "The best church of God..."
In churches are served the holy services, and the spirit of God dwell within them. The soul, however, is the best church of God, and whoever prayers internally, for him the whole world has become a church of God.
This, however, is not for everyone. Many pray externally, or prefer to pray with books. This is also good, and the Lord accepts their prayer.
If someone, however, prays, but thinks about other things, the Lord does not hearken to his prayer.