Pastor Josh Troester's sermon "Level-One Christianity Part 3" stresses the importance of a strong foundation in faith, referencing 2 Peter 1:3-11. He focuses on the eight building blocks of faith, virtue, knowledge, self-control, steadfastness, godliness, brotherly affection, and love as essential for believers. Pastor Troester explains that true faith leads to transformation, urging his congregation to confirm their calling through these qualities. Through illustrations and explanations, he emphasizes the necessity of these qualities to live a fruitful Christian life and remain under Christ's protection.