“If in this life only we have hope in Christ, we are of all men most miserable.”-1 Corinthians 15:19

The apostle is arguing with professedly Christian people, who were dubious about the resurrection of the dead. He is not saying that all men are now miserable if there be no hope of the world to come, for such an assertion would be untrue. There are very many who never think of another life, who are quite happy in their way, enjoy themselves, and are very comfortable after a fashion. But he speaks of Christian people-“If we, who have hope in Christ, are led to doubt the doctrine of a future state and of a resurrection, then we are of all men most miserable.” The argument has nothing to do with some of you who are not Christians; it has nothing to do with you who have never been brought out of a state of nature into a state of grace; it only respects those who are real, living followers of the Savior, and who are known by this, that they have hope in Christ-hope in His blood for pardon, in His righteousness for justification, in His power for support, in His resurrection for eternal glory. “If we who have hope in Christ, have that hope for this life only, then we are of all men most miserable.” You understand the argument; he is appealing to their consciousness; they, as Christians, had real enjoyments, “but,” says he, “you could not have these enjoyments if it were not for the hope of another life; for once take that away, if you could still remain Christians and have the same feelings which you now have, and act as you now do, you would become of all men most miserable,” therefore to justify your own happiness and make it all reasonable, you must admit a resurrection; there is no other method of accounting for the joyous peace which the Christian possesses. Our riches are beyond the sea; our city with firm foundations lies on the other side of the river; gleams of glory from the spirit-world cheer our hearts and urge us onward; but if it were not for these, our present joys would pine and die. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/0562.cfm