We are sheep; Jesus is the gate for the sheepfold.  The imagery is simple and ancient.  Here there is not “heaven” but instead a place of safety and security from the world with its dangers and threats.  Even this place of safety is not entirely secure, as there are some thieves and robbers who would climb the fence, not entering through the gate.  Our only “protection” from such dangers is that we would not follow their voice.  Let us know the gate through which we enter the sheepfold and not be called away by other voices.