John Calvin Commentary Galatians 1:22

"And I was still unknown by face unto the churches of Judaea which were in Christ:" — Galatians 1:22 (ASV)

And was unknown by face. This appears to be added to show more strongly the wickedness and malignity of his slanderers. If the churches of Judea, who had only heard about him, were led to give glory to God for the astonishing change which he had worked in Paul, how disgraceful it was that those who had witnessed the fruits of his amazing labors should not have acted in the same way! If the mere report was enough for the former, why did the facts before their eyes not satisfy the latter?