We're not all perfect and we do err. Paul told the Romans that "for all have sinned and fall short of the glory of God" (Rom 3:23). But how do people err? There are several ways that this can occur. One way is through ignorance. Jesus said "Is this not the reason you are mistaken, that you do not understand the Scriptures, or the power of God?" (Mark 12:24). Some do not even take the time to understand the scriptures and as a result will continue in ignorance all their lives. Some have professed Jesus Christ but then stray from the faith as Paul points out in 1 Tim 6:21. In this day and time deception plays a key role with why people err. People want to believe something so bad that they will practically do anything to twist the scriptures to make it fit their liking, or they'll try to find a church that is teaching all the things that "they" agree with, not that they are right in the sight of God. People are deceived and do not test the spirits to find out if it is indeed the "oracles of God". We can know the difference between the spirit of truth and the spirit of error. Take a few moments to read 1 John 4:1-6. These few passages clearly point out the differences. People often err because of weakness. Our fleshly bodies are weak and have a tendency to give into temptation. That is why Jesus warns "Keep watching and praying, that you may not enter into temptation; the spirit is willing, but the flesh is weak" (Matt 26:41). It takes an effort on our part to keep ourselves focused on Jesus Christ and his righteousness.
Covetousness causes people to err. Many good Christian brethren have fallen due to covetousness. Paul tells Timothy that "money is the root of all sorts of evil and some by longing for it have wandered away from the faith, and pierced themselves with many a pang" (1 Tim 6:10). There is yet another cause that is hurting the church today and that is that Christian brethren begin to err because of the company they keep. Paul warned "do not be deceived, bad company corrupts good morals" (1 Cor 15:33). Again deception plays a part in this area and if we are not careful we will separate ourselves from the Lord. We need to be very careful who we associate with.
When we see erring brethren we have a responsibility to get them back on the path that leads to heaven. We need to warn against err when we see it happening as pointed out in Matt 18:15 and Luk 11:3. We need to admonish them - let them know that they are not behaving in a godly manner (2 Thes 3:15). In addition we need to pray for them (Jam 5:16), convert them back to Christianity (Jam 5:20), and restore them (Gal 6:1). When we talk to a brother or sister that is erring we need to be careful about how we handle the situation. Getting angry, upset, and mad at them will not usually turn them around. We are to deal with the erring gently. Paul taught the Galatian brethren that "even if a man is caught in any trespass, you who are spiritual, restore such a one in a spirit of gentleness; each one looking to yourself, lest you too be tempted" (Gal 6:1). See also Heb 5:2. No one is perfect as I pointed out at the front of this article and we need to ensure that we treat others as we would like to be treated in any given situation (Matt 7:12). A spirit of gentleness will go much further in restoring an erring brother than a tough "I'm better than you" attitude.
Once one realizes the errors of their way, then they can return to the fold by repenting (Acts 8:22; Rev 2:5), confessing (Jam 5:16; 1 John 1:9), and by praying to God for forgiveness of their sins (Acts 8:22). Afterward, we have a duty toward the erring. We must forgive them (2 Cor 2:7), love them (2 Cor 2:8), and comfort them (2 Cor 2:7). We should actively strive to restore any erring brother because it is our duty (Matt 18:15) and it is our goal to want to save all from the grasp of Satan, so that all can be saved (Jam 5:20).