Are you happy?
An atheist was once addressing a crowd of people in the open air. He was trying to persuade them that there was no God and no devil, no heaven, and no hell, no resurrection, no judgment, and no life to come. He advised them to throw away their Bibles, and not to pay attention to what preachers said. He recommended them to think as he did, and to be like him. He talked boldly. The crowd listened eagerly. It was "the blind leading the blind." Both were falling into the pit (Matthew 15:14).
In the middle of his address a poor old woman suddenly pushed her way through the crowd, to the place where he was standing. She stood before him. She looked him full in the face. "Sir," she said, in a loud voice, "Are you happy?" The atheist looked scornfully at her, and gave her no answer. "Sir," she said again, "I ask you to answer my question. Are you happy? You want us to throw away our Bibles. You tell us not to believe what preachers say about Christ. You advise us to think as you do, and be like you. Now before we take your advice we have a right to know what good we will gain by it. Do your fine new ideas give you a lot of comfort? Do you yourself really feel happy?"
The atheist stopped, and attempted to answer the old woman's question. He stammered, and shuffled, and fidgeted, and endeavored to explain his meaning. He tried hard to return to the subject. He said, he "had not come to preach about happiness." But it was of no use. The old woman stuck to her point. She insisted on her question being answered, and the crowd took her side. She pressed him hard with her inquiry, and would take no excuse. And at last the atheist was obliged to leave, and sneak off in the confusion. His conscience would not let him stay: he dared not say that he was happy.
(taken from Practical Religion, by J.C. Ryle)
I do not think this is a hard and fast rule, per se. There are people who seem very happy and content without being Christians, and a lot of Christians who are not happy or content.
But even so, I am often struck by the stark difference between the empty life of self-service and the joyful life of submission and service to God.
Recently, I realized I've almost entirely let go of apologetics. I used to be very much into the creation-evolution debates, arguments about reality, or technical discussions of Biblical accuracy. Those things are still good: I think it is wise for Christians to have a good understanding of them. But for as for me, my trust is in God because of the works he does; the way he has shaped and molded me through experience, the way his answers are always the healthier answers, and the way he speaks to me through my own prayers.
Though I tend toward sorrow and struggles with depression, I still find my joy in the hope of the gospel and the glory of God. I believe relationships can be healed through the strength of the Spirit even when my strength wanes. I know my purpose is tied to my obedience and not my competance. And I am happy, because God is real and all he says and does is right.