Whatever happened to sin?

I'm not the first to ask.  Many more learned people than I have posed the question.  The question arose as I was reading this story concerning the change in leadership at Robert Schuller's Crystal Cathedral.  Schuller, well known for his "positive," feel-good, self-esteem promoting messages, is quoted in the article as saying,

"The real minister's name that we honor is Jesus, not Schuller," he said to thunderous applause, according to the Los Angeles Times. "I was called to start a mission, not a church," Schuller said. "You don't try to preach . . . what is sin and what isn't sin."

Oh. 

Good thing Jesus (all quotations from the ESV) never told anyone, "..from now on sin no more." (John 8:11)  Good thing Jesus never told people seeking answers to injustice in Luke 13:1-5: "There were some present at that very time who told him about the Galileans whose blood Pilate had mingled with their sacrifices. And he answered them, "Do you think that these Galileans were worse sinners than all the other Galileans, because they suffered in this way?  No, I tell you; but unless you repent, you will all likewise perish.  Or those eighteen on whom the tower in Siloam fell and killed them: do you think that they were worse offenders than all the others who lived in Jerusalem?  No, I tell you; but unless you repent, you will all likewise perish."  Good thing?  Uhhh, no.  The right thing is what Jesus did.  So did the apostles in their preaching and teaching.

Is not one of the problems in the church today, the redefining of sin, if we talk about it at all?  Is not sin why we need a Savior?  If we "don't try to preach . . . what is sin and what isn't sin," per Dr. Schuller, then how is what we teach ultimately any different than good moralistic citizenship with a pot of gold at the end of the rainbow?  If we do not talk or define sin, then how do we talk about or define sanctification and holiness?  How do we evangelize biblically?

Michael Horton has addressed the issue here and here.