He was speaking to those only who had eyes to see and ears to hear. The Gate is narrow and few find it. He is the gate.

Obstinate unbelief will have something to say, though ever so unreasonable. Christ refused to answer their demand. If they will not be convinced, they shall not. Alas! what cause we have to lament for those around us, who destroy themselves and others by their perverse and obstinate unbelief, and enmity to the gospel! When we forget the works of God, and distrust him, we should chide ourselves severely, as Christ here reproves his disciples. How is it that we so often mistake his meaning, disregard his warnings, and distrust his providence?

Mark 8:11-21