A.T. Robertson Commentary Matthew 21:25

"The baptism of John, whence was it? from heaven or from men? And they reasoned with themselves, saying, If we shall say, From heaven; he will say unto us, Why then did ye not believe him?" — Matthew 21:25 (ASV)

The baptism of John (το βαπτισμα το Ιωανου). This represents his relation to Jesus who was baptized by him. At once the ecclesiastical leaders find themselves in a dilemma created by their challenge of Christ.

They reasoned with themselves (διελογιζοντο). Picturesque imperfect tense describing their hopeless quandary.