Final answer:
The main theme in the verse 2 Corinthians 10:3-5 is the power of prayer in Christianity, emphasizing the spiritual aspects over physical or worldly methods in combating sin and aligning with God's will.
Step-by-step explanation:
The main theme or revelation that supports Christianity in the verse 2 Corinthians 10:3-5 is (c) The power of prayer. This passage speaks about the spiritual warfare that Christians engage in and how they combat through prayer and divine power rather than physical violence. The apostle Paul emphasizes that while Christians live in the world, their methods of fighting spiritual battles are not worldly but powered by God to demolish strongholds and take every thought captive to obey Christ. This echoes the major theme throughout the early Christianity period where faith, prayer, and divine intervention were considered the ways to overcome sin and to live according to God's will, as shown through St. Paul's teachings and Martin Luther's realization that salvation is by faith alone, not through good works.