that is only to prove your faith is sterling (far more precious than gold which is perishable and yet is tested by fire), and it redounds to your praise and glory and honour at the revelation of Jesus Christ.
strengthening the souls of the disciples, encouraging them to hold by the faith, and telling them that "we have to get into the Realm of God through many a trouble."
They withdrew from us, but they did not belong to us; had they belonged to us, they would have remained with us, but they withdrew to make it plain that they are none of us.