Is the church found in the Old Testament or the Gospels?
The church is not found in the Old Testament, nor is the Body of Christ found in the Gospels. It is strictly a Pauline revelation, part of the mysteries revealed to Paul, the grace doctrine kept secret and hidden in God's mind until revealed.
Les teaches that you will find nothing of the church in the Old Testament, and nothing of the body of Christ in the Gospels. Instead, it is strictly a Pauline revelation. After Saul was converted, God took him out of Damascus and, as Les understands it, down to Mount Sinai, where for three years in a private, solitary seminary training God revealed to Paul the mysteries. Those mysteries become the whole sphere of grace doctrine. Paul constantly appeals that these revelations of grace doctrine were revealed to him, and that up until that time it had been kept secret and hid in the mind of God. This connects back to Genesis, where one of the names of deity at the time of Abraham showed He was the eternal, sovereign Creator God who could hide things if He wanted to.