A.T. Robertson Commentary John 7:27

"Howbeit we know this man whence he is: but when the Christ cometh, no one knoweth whence he is." — John 7:27 (ASV)

Howbeit (αλλα). Clearly adversative here.

This man (τουτον). Possibly contemptuous use of ουτος as may be true in 25,26.

Whence he is (ποθεν εστιν). The Galilean Jews knew the family of Jesus (6:42), but they knew Jesus only as from Nazareth, not as born in Bethlehem (verse 42).

When the Christ cometh (ο Χριστος οταν ερχητα). Prolepsis of ο Χριστος and indefinite temporal clause with οταν and the present middle subjunctive ερχητα rather than the more usual second aorist active ελθη as in verse 31, a trifle more picturesque. This is a piece of popular theology. "Three things come wholly unexpected--Messiah, a godsend, and a scorpion" (Sanhedrin 97a). The rulers knew the birthplace to be Bethlehem (7:42; Matthew 2:5f.), but some even expected the Messiah to drop suddenly from the skies as Satan proposed to Jesus to fall down from the pinnacle of the temple. The Jews generally expected a sudden emergence of the Messiah from concealment with an anointing by Elijah (Apoc. of Bar. XXIX. 3; 2Esdr. 7:28; 13:32; Justin Martyr, Tryph. 110).