If there is no Valhalla, Shangri-La, Elysium Fields, Heaven, etc. then this is the only life we have and we should make every moment count for something and for someone because our actions have very clear material consequences. If those places exist, then we should make every moment count for something and for someone because our actions have consequences even after our death.
I would like to say that I am afraid of death. I'm more afraid of the process that leads to death, the possible pain or the unknown moment of when I'm going to die. The concept of death itself doesn't bother me, and it is for the above reason; I either won't know I am dead, or I will know I am dead and be waiting for my loved ones while I enjoy what happens next.
Maybe I'm over-optimistic here, but I don't believe that Hell has any sway in where I am going. If Jesus did what was written of him, then Hell is empty. That means Hitler, Gays, Jews, Atheists, and everyone else that "Christians"* say are in Hell have been forgiven,.
St. Gregory of Nyssa believed that ultimately, all creatures will be reconciled to God. Unfortunately, that teaching didn't catch on.
The Eastern Orthodox generally hold that Orthodoxy is the true faith, and better conduces to union with God than any other religion or any other form of Christianity, but don't make any blanket statements about the fate of non-Christians or heterodox Christians. I remember my pastor once asking me if I had heard of these fundamentalists who "really think that people who don't believe as they do will go to hell." He thought it was an odd and somewhat amusing belief.
It is the opinion of Father George Papademetriou that "the non-Christian may be saved in spite the religion he practices, but only through the mercy of God." St. Theophan the Recluse, asked whether it was possible for the heterodox to be saved, answered, "Why do you worry about them? They have a Saviour Who desires the salvation of every human being. He will take care of them. You and I should not be burdened with such a concern. Study yourself and your own sins." Bishop Kallistos (Ware) wrote, "It is heretical to say that all must be saved, for this is to deny free will; but it is legitimate to hope that all may be saved."
In the Catholic Church, at least three of the last four popes have affirmed that it's possible for non-Christians to be saved. (I don't know about John Paul I.) The Catholic Catechism says:
1260 "Since Christ died for all, and since all men are in fact called to one and the same destiny, which is divine, we must hold that the Holy Spirit offers to all the possibility of being made partakers, in a way known to God, of the Paschal mystery." Every man who is ignorant of the Gospel of Christ and of his Church, but seeks the truth and does the will of God in accordance with his understanding of it, can be saved. It may be supposed that such persons would have desired Baptism explicitly if they had known its necessity. That seems to imply that people who are ignorant of Christianity have an advantage over people who have heard of Christianity but reject it, which reminds me of the story of the missionary and the Eskimo.
"If I didn't know about God," asked the Eskimo, "would I go to hell?"
"No," said the missionary, "not if you didn't know."
"Well then, why did you tell me?"
I don't know what Luther thought about it. Zwingli thought it was possible for non-Christians to be saved, and Calvin (predictably) did not. There is, however, a small group of Calvinist Baptists in the Appalachian region, the Primitive Baptist Universalists, popularly known as the "No-Hellers," who believe everyone will be saved. They believe that Christ died for the sins of all mankind, and so you will be saved whether you like it or not.
SO STOP WORRYING ABOUT ARMAGEDDON!
*Christians in this sense are those who speak of love, and enact hate. I believe in the true meaning of the word, which means Christlike.