Why didn't He do many mighty works there?

Matthew 13:57-58(NKJV)

So they were offended at Him. But Jesus said to them, “A prophet is not without honor except in his own country and in his own house.” 

Now He did not do many mighty works there because of their unbelief.

 

Hmm.  Did Jesus not do many mighty works there as a punishment for their unbelief or was it their unbelief itself that stopped the mighty works from happening?