Mark 11:31

31 And they argued with one another, "If we say, 'From heaven,' he will say, 'Why then did you not believe him?'

Mark 11:31 Meaning and Commentary

Mark 11:31

And they reasoned with themselves saying
Privately; perhaps, they withdrew at a little distance for a short time, and consulted among themselves what answer to return; and the amount of their reasonings were this;

if we shall say from heaven, he will say, why then did ye not
believe him?
that is, should they say that John had a divine commission for what he said and did, they were aware that Christ would reply, why did not ye give credit to him? and had you done so, seeing he testified of me, you would have had no occasion to have put the above question; (See Gill on Matthew 21:25).

Mark 11:31 In-Context

29 Jesus said to them, "I will ask you a question; answer me, and I will tell you by what authority I do these things.

30 Was the baptism of John from heaven or from men? Answer me."

31 And they argued with one another, "If we say, 'From heaven,' he will say, 'Why then did you not believe him?'

32 But shall we say, 'From men'?" --they were afraid of the people, for all held that John was a real prophet.

33 So they answered Jesus, "We do not know." And Jesus said to them, "Neither will I tell you by what authority I do these things."