How do we know that serving God leads to true fulfillment?

Serving God is rooted in the understanding that true fulfillment comes from a relationship with the Creator, rather than from earthly success or recognition. In John 15:5, Jesus states, 'I am the vine, you are the branches. He who abides in Me, and I in him, bears much fruit; for without Me you can do nothing.' This signifies that genuine purpose and fulfillment stem from being connected to Christ. Additionally, the Duke of Sully is portrayed as a man who, despite worldly achievements, did not possess the deeper fulfillment that service to God grants. As Christians, we recognize that our ultimate reward lies not in this life but in the eternal inheritance prepared for us, as outlined in 1 Peter 1:4.