Life is without ultimate meaning. If each individual person passes out of existence when he dies, then what ultimate meaning can be given to his life? Does it even matter than he existed or not? It might be said that his life was important because it influenced others or affected the course of history but that only shows a relative significance to his life, not an ultimate significance. If all of the events are ultimately meaningless then what significance is there in influencing any of them. Mankind is destined only toperish in the eventual heat death of the universe. The contribution of the scientist to the advance human knowledge, the practices of doctors and nurses to alleviate pain and suffering, the efforts of the diplomat to secure peace in the world, the sacrifices of good people everywhere to better the lot of the human race.In the end all of these come to nothing, they don't make one bit of difference. Therefore each persons life is without ultimate significance and because our lives are ultimately meaningless, the activities that we fill our lives with are also, in the final analysis, meaningless. The long hours spent studying, our friendships, our interest, our jobs, our relationships, all of these are, in the final analysis, ultimately meaningless. This is the horror of modern man, because he ends in nothing, he ultimately is nothing.
If life ends at the grave, it ultimately makes no difference if you live as a Stalin or a saint. If there is no immortality then all things are permitted. "Live totally for self, no one holds you accountable, indeed it would be foolish to do anything else for life is too short to jeopardized it, by acting out of anything but pure self interest" Sacrifice for another person would be stupid. There is no ultimate purpose without immortality and God. If death stands at the door with open arms at then what is the goal of life? To what end has life been? Has it all been for nothing? Is there no purpose for life at all?
If there is no God, then your life is not qualitatively different from that of a dog. The old testament book, Ecclesiastes, writes "For the fate of the sons of men and the fate of animals are the same. As one dies so dies the other. Indeed they have all the same breath and there is no advantage of man over animal for all is meaningless." If life ends at the grave then life is objectively meaningless.
Reasonable faith
The Absurdity of Life apart from God
William Lane Craig