"I don't know how anyone can tell me with a straight face that an all-forgiving, all-loving, compassionate God would condemn anyone to eternal pain and agony in the bowels of Hell for eternity just for the actions of a mere 90 years on this planet."
The Bible doesn't say that God is all-forgiving and all-loving. You are creating an "idol"--making up a false god in your mind. God is holy and just as well as loving and merciful. His love is seen in that He gave you the gift of life. His mercy is seen in allowing you to sin against Him. But if you refuse to repent and end up dying in your sins, He will give you absolute justice, and that's a fearful thing. Damnation means forever being damned from all the pleasures He lavished upon you, for which you were so unthankful.