Mark 8:11-13
Chapter 8
11
They Ask Him for a Sign from Heaven
The Pharisees approached and began to argue with Jesus. Wanting to embarrass him, they asked for a heavenly sign.12
He sighted from the depth of his spirit and said:
“Why do the people of this generation ask for a sign? Truly, I say to you, no sign will be given to this people.”
13
Then he left them, got back into the boat, and went to the other side of the lake.

Commentaries
They Ask Him for a Sign from Heaven – The Blindness of the Disciples.
The Pharisees ask Jesus for a sign. Jesus uses this moment to teach that the signs or miracles he performs are acts of mercy and solidarity; they are not meant to persuade people to believe. A faith based on miracles produces believers without true commitment. Faith cannot rely on miracles; instead, miracles depend on faith. Yeast (15) here symbolizes a negative influence of fermentation, which causes the bread of misunderstanding and unbelief to rise—a trait of the Pharisees and Herodians (cf. 3:6). The focus then shifts to the disciples. Jesus questions them sternly, rebuking their lack of belief and understanding by comparing it to that of their critics.