Jesus used simple illustrations to reach the heart. When someone said, “I will follow You wherever You go,” He responded this way:
As they were going along the road, someone said to Him, “I will follow You wherever You go.” And Jesus said to him, “The foxes have holes and the birds of the air have nests, but the Son of Man has nowhere to lay His head.” (Luke 9:57-58 NASu; see Matthew 8:19-20)
William Barclay, in The Daily Study Bible, comments on this account at Matthew 8:19-20.
It is as if Jesus said to this man: “Before you follow me—think what you are doing. Before you follow me—count the cost.
Jesus did not want followers who were swept away by a moment of emotion, which quickly blazed and just as quickly died. He did not want men who were carried away by a tide of mere feeling, which quickly flowed and just as quickly ebbed. He wanted men who knew what they were doing. He talked about taking up a cross (Matthew 10:38). He talked about setting himself above the dearest relationships in life (Luke 14:26); he talked about giving away everything to the poor (Matthew 19:21). He was always saying to men: “Yes, I know that your heart is running out to me, but—do you love me enough for that?”
Jesus still demands full allegiance.