There is an interesting passage in the Bible about building, or repairing, the wall of Jerusalem when the Jews returned there from captivity in the days of Ezra and Nehemiah. You can read this passage in Nehemiah chapter 3. Nehemiah is inspired by God to record in detail what part of the wall each person worked on and in some cases how well they worked (or didn't - see verse 5). We do not find any similar account in the Old Testament before this. The closest I can recall is the record of the exploits of David's mighty men and the contributions of others also, in 1 Chronicles chapters 11 and 12, where a number of individual men are named, along with their accomplishments and responsibilities.
Examples in the Bible are written for our learning. What is God teaching us here?
One lesson might be simply that God knows our works, each one of us individually, so that He can reward us according to our works, just as He knew the individual accomplishment and work of each of David's mighty men and each person who worked on building or repairing the wall in Nehemiah's time (Matthew 16:27, John 4:36-38, Hebrews 6:10, Matthew 25:14-30, Luke 19:11-26).
But with the wall, there may be another lesson.
The wall around a city was the protection of the city. Jerusalem may represent the Church, and the men building or repairing the wall may represent the members of the Church who each individually has a responsibility to do his or her part to protect the Church of God from Satan's and the world's influence.
And God pays attention to how well each of us does his part of that job.
Just as each of the men who built or repaired the wall had a portion of the wall he was responsible for, so each of us has a portion of the Church he or she is responsible for protecting from wrong spiritual influences and from sin.
What is that portion?
Collectively, we are the Church of God, the body of Christ. We each protect the Church, "repair the wall" so to speak, by guarding OUR OWN MINDS from sin and from Satan's and the world's temptations and influences. My own mind is the portion of God's Church I must protect. Your mind is the portion of God's Church you must protect.
Figuratively speaking, this is like the responsibility each Jew who worked on the wall had to repair his portion of the wall to protect Jerusalem.
Our portion of the wall is the wall of our own mind. We need to protect it from the evil influences of Satan and this world.
How can we do this? We do it by fleeing temptation (1 Corinthians 6:18, Matthew 5:29-30). We can avoid this world's entertainment, which is Satan's educational system, his school for training the world in his way of life. We can strengthen the walls of our mind with Bible study, prayer, meditation, and fasting.
The responsibility is ours, and as we each protect our mind, we also protect the Church, because we are the Church.
And just as God kept track of how each Jew in Nehemiah's day worked on the wall around Jerusalem, so God sees and remembers how each of us protects that part of the Church of God that is our own mind.