In 2 Cor.11: 2-3, Paul spoke about how he was leading them to be engaged to Jesus Christ to be married to Jesus one day. He had a tremendous jealousy that they should not fall in love with anybody on the way.
Think of Abraham's servant who was taking Rebecca all the way, 40 miles, to Isaac. During that time if some handsome young fellow came along and tried to win Rebecca's affection, what would Eliezer have done? He would have said, "Get away. She is booked for my master's son." He would tell her, "Don't be attracted by all these fellows."
Paul wanted to preserve the church in Corinth like that for Jesus. That's a jealousy. "You are reserved for Jesus. You cannot live for the world, money or honour. Other fellows may come and attract you. I want you to live for God."
A true servant of God has a jealousy like that for His people; that they should be kept like a pure virgin for Christ. But he said, "I am afraid that Satan will come like the old serpent in Eden came cunningly and drew Eve away. I am concerned that your heart will be drawn away from the devotion to Jesus Christ."
How do you know that you have become a backslider? How do you know that you have gone astray? Is it when you believe some wrong doctrine? According to 2 Cor. 11:3, you have gone astray the moment you lose your devotion to Jesus Christ. That's the mark of going astray. Every believer who has lost his devotion to Jesus Christ has gone astray already. And our job as servants of God is to preserve them in devotion to Jesus Christ. That's the most important thing.
The devil is always seeking to lead believers astray from their devotion to Jesus Christ, from fervently loving Him. What's the use of serving Him, doing evangelism, teaching or building the church when we have lost our love for Jesus Christ?
The Lord told the church in Ephesus, "What's the use of doing so many good things when you don't love Me like you used to do at first? I don't want all your service." Please remember to keep yourself in a devotion to Christ and to keep others whom we serve in devotion to Christ.