His main idea is that people are not looking for faith/freedom, but rather looking for security and food, and that Jesus would have done a lot better if this is what he offered.  This, it argues, is why the Church has been so successful.  Rather than having to struggle to find faith, people turn to the Church that tells them what to believe, how to express their faith, and how to be saved.  When Jesus was tempted in the desert, his remark was that man "does no live by bread alone."  The Inquisitor tells him that he would have done better to provide them with bread because people who are hungry, whose attention is taken up by the fight to stay alive, don't have free will and cannot turn their attention to faith.

But the Church is not without blame, because the Inquisitor says the Church has used its power to enslave people rather than to free them to find real faith.  In fact, the Inquisitor  has to burn Jesus at the stake to make sure that he does not disturb the people's peace and the Church's power.

But Jesus defeats their power with the same power of love that he preached.  They expect Him to argue His case, but instead he approaches the Inquisitor and gently kisses him.  Instead of killing Jesus, the Inquisitor takes him to the alley and tells him to go and never, never return.  And Jesus walks away, reminding us of the truth that Jesus will never enter our lives without our first inviting him in.