The sermon explores the contrast between the eternal nature of God and the fleeting brevity of human life, drawing primarily from Psalm 90. It challenges listeners to consider the central theme of their existence by recognizing that life is short and subject to divine judgment. The message urges believers to number their days wisely, avoiding the waste of time through murmuring or sin, and instead pursuing Christ as the ultimate wisdom. It emphasizes that while humans are frail and finite, God remains an everlasting refuge and a source of loyal mercy for those who repent. Ultimately, the preacher calls for a life of intentional obedience and reliance on God's grace to establish meaningful work that endures beyond this temporary existence.