Shane Idleman discusses the themes of contention, contending, and worldliness in the context of Acts chapter 10, where Peter shares the gospel with Cornelius, a Gentile. He emphasizes the difference between being contentious and contending for the faith, highlighting the importance of a loving and humble approach when addressing issues within the church. Idleman encourages believers to be discerning in their interactions with the world, advocating for a balance between engaging with sinners and maintaining one's faith. He stresses the necessity of prayer, godly counsel, and the pursuit of love as foundational to effective ministry and spiritual growth.