Let's be clear about one thing: Jesus didn't say what this guy said. People go to hell because they are unrepentant and unregenerate. It's not clear that someone who is remarried after a divorce can't repent, and is necessarily unregenerate. The pastor's (rather inflammatory, don't you think?) claim is deeply problematic in that it undercuts the entire basis for Jesus' death on the cross in that it makes our salvation entirely dependent upon our behaviors and actions, rather than on Jesus' saving works.