Dear Phil (duck dynasty) Robertson, Thank you for educating people regarding God's Law

[CthulhusEvilCousin]

22. The quote I provided

is a reference to hell, or at least eternal punishment for the wicked, which requires, naturally, life after death in order to enforce. As for life after death in general, there isn't just 'vague references' to it. It's rather a required understanding. For example, Saul goes to the witch of Endor for the very purpose of bringing up the spirit of Samuel:

"Then said the woman, Whom shall I bring up unto thee? And he said, Bring me up Samuel. And when the woman saw Samuel, she cried with a loud voice: and the woman spake to Saul, saying, Why hast thou deceived me? for thou art Saul. And the king said unto her, Be not afraid: for what sawest thou? And the woman said unto Saul, I saw gods ascending out of the earth. And he said unto her, What form is he of? And she said, An old man cometh up; and he is covered with a mantle. And Saul perceived that it was Samuel, and he stooped with his face to the ground, and bowed himself. And Samuel said to Saul, Why hast thou disquieted me, to bring me up? And Saul answered, I am sore distressed; for the Philistines make war against me, and God is departed from me, and answereth me no more, neither by prophets, nor by dreams: therefore I have called thee, that thou mayest make known unto me what I shall do."
(1Sa 28:11-15)

As for Isaiah. Isaiah is a huge book with many prophecies, so, of course no one would say that the entire book is about the Messiah. But, that the book contains Messianic prophecies, there is no question. For example, from Joseph Ben Uziel, 30 years before the birth of Christ, paraphrasing from Isaiah:

“Ye are my witnesses, saith the Lord, and my servant, the Messiah, in whom is my delight, in order that ye may know, and that ye may believe in me, and understand that I am He who was from the beginning ; yea, ages after ages are mine, and beside me there is no God.” (The Chaldee paraphrase on the prophet Isaiah [by Jonathan b. Uziel] tr. by C.W.H. Pauli)