THe Church established by using the Bible as a secular document

Fr William Most made this argument
FACT 1: There was a man called Jesus.
FACT 2: He claimed to be a messenger sent by God.
FACT 3: He did enough to prove that He was such a messenger.
Now the mere fact of working miracles would not prove that Jesus was a messenger sent from God. It is probable that God at times worked miracles even for good pagans. But Jesus often appealed to His miracles as proof of His mission and teaching (see, among these, Matthew 11:2-5, Luke 7:20-22, Mark 2:9-11). Now God is the ultimate source of the miraculous power; but He, being Truth, cannot provide such power as proof of a falsehood. So Jesus' claims were proved true. In fact, He proved that He could even forgive sins. A most remarkable messenger!
FACT 4: Crowds followed Christ. But He had an inner circle to whom He spoke more intimately. This is merely what we would expect.
FACT 5: He told His followers to continue His teaching.
FACT 6: Jesus gave the message that God would protect that teaching: "He who hears you hears me; he who rejects you rejects me, and he who rejects me rejects him who sent me" (Luke 10:16).

In summary then, we see a group that is commissioned to teach by a messenger sent by God, and promised God's protection for that teaching. These observations are made without treating the Scriptures as inspired.