"We're all infected." Those words of revelation splattered from the protagonist, Rick's, mouth sent chills down the rickety spines of the survivors. The CDC's worst-case scenario prediction - the infection is in every person - has come to pass. You no longer need a bite or a chomp from one of the undead. Once you die, you simply become one of them. You join the ranks of the living dead.
No one is truly safe now. The farm that was supposed to protect the survivors had been run over by walkers. There is no safe house anywhere anymore. Perhaps the one who had his world turned upside down was Hershel as he watched his refuge go up in flames. His sardonic reference to the promise of the "resurrection of the dead" only added fuel to the fire of the desolation of the survivors. Unless salvation arrives soon, they too will join the ranks of the horde - the walking dead.
As the finale rolled out in pure gore and desperation, I cannot help but think that the death motifs are akin to and beautiful tributes to the religious concepts of sin and the hopelessness of the human condition.