"Welcome Sinners!"

what kind of greeting is this

John said to the crowds that came out to be baptized by him, "You brood of vipers! Who warned you to flee from the wrath to come? Bear fruits worthy of repentance. Do not begin to say to yourselves, 'We have Abraham as our ancestor'; for I tell you, God is able from these stones to raise up children to Abraham. Even now the ax is lying at the root of th…