I suspect this is much more common today than in previous generations, because over time, our society has become much more secular and materialistic. Even if someone was not a believer, his or her relatives usually wanted the person's funeral to have a religious tone.
But if someone has no belief in God or in eternity–as is true of many people today–then they only believe in this world. To put it another way, life for them consists only of this world's activities and pleasures, and they never give any thought to the fact that this life is not all there is, and someday they will enter eternity and must meet God. Like Job in the midst of his despair, they believe that "My days are swifter than a weaver's shuttle, and they come to an end without hope" (Job 7:6).
But this life is not all there is! We were created in the image of God, and we each have an immortal soul that lives forever–either with God in heaven, or in that place of absolute despair the Bible calls hell. The Bible solemnly warns, "Man is destined to die once, and after that to face judgment" (Hebrews 9:27).
When we know Christ, however, we need not fear God's judgment, for we know that Christ has already taken upon Himself the judgment we deserve. Instead, we have hope–the hope of heaven. Have you put your faith in Christ for your salvation?