Dr. Roger Smith's sermon, centered around the theme "Invest," encourages the congregation to actively participate in God's kingdom. He draws parallels from the early church in Acts, emphasizing their devotion to the apostles' teachings, fellowship, breaking bread, and prayers. Dr. Smith emphasizes the need to invest time, energy, and resources in these areas, not for personal gain, but for spiritual growth and the expansion of God's kingdom. He highlights that true investment requires faith, trust, and a willingness to let go of selfish desires, reminding the congregation that God promises exponential, eternal returns on their investments. The sermon concludes with a call to action, urging the congregation to reflect on their personal investment in God's kingdom and to actively seek opportunities to love and serve one another.