Based on sermons from Piper (1, 2), MacArthur (1, 2), and Spurgeon
Piper summarizes the first verses thusly: “You are forgiven! You know Christ! You have conquered the devil! So be encouraged! Abide in Christ! Use his truth and power to avoid error and to defeat the temptation to sin.” Spurgeon notes that little children need only to know the Father, and rejoice in his love; in the days of their strength, young men overcome the wicked one who would easily have overcome them if left to fight in their own strength; knowing him that is from the beginning is all that even the fathers need to know or can know, for this knowledge includes all other that is worth knowing. These verses give us hope and courage to fight evil – we have overcome the darkness; we can keep God’s commandments; we can love each other with a divine love so great that the world will notice and glorify God! And the weapon that defeats evil is the Word of God abiding in us.
Growth is evidence of life, both in the physical and spiritual realm. Becoming like Christ is the goal and the objective of the process of spiritual maturity. You are sanctified when you are saved and set apart from sin, but you will be fully sanctified when you enter into heaven’s glory and eternally separated from sin. Between these times we should be daily becoming more like Christ.
MacArthur says, “Now there are a number of ways in which the Bible defines spiritual growth. It calls it ‘following after righteousness,’ (1 Tim. 6:11). It calls it ‘being transformed by the renewing of your mind,’ (Rom. 12:2). It calls it ‘perfecting holiness in the fear of God,’ (2 Cor. 7:1)... it calls it ‘pressing toward the mark’ (Phil. 3:14). Colossians 2:7 says, ‘It's being built up in the faith.’ Paul at the very end of his life [said], ‘I'm the chief sinner.’ Because as you mature there's a decreasing frequency of sin but there's an increasing hatred of sin that makes less sin seem worse.”
Jesus taught the first and great commandment as “You shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength.” Love for the world pushes out love for God, and love for God pushes out love for the world. Jesus also said, “No one can serve two masters; for either he will hate the one and love the other, or he will be devoted to one and despise the other. You cannot serve God and wealth” (Matthew 6:24). Piper says, “Not only is the world passing away, but also the lusts of it. If you share the desires of the world, you will pass away. You will not only lose your treasure. You will lose your life. If you love the world, it will pass away and take you with it.” In John 5:44 Jesus confronts the unbelieving Jewish leaders with these words, “How can you believe, when you receive glory from one another and you do not seek the glory that is from... God?” They loved the world (the glory of men) not the glory of God.
“Anything in this world that is not God can rob your heart of the love of God. Anything that is not God can draw your heart away from God. If you don't have it, it can fill you with passion to get it. If you get it, it can fill you with pride that you've got it” (Piper). Whatever you do in word or deed, do all in the name of the Lord Jesus, giving thanks through Him to God the Father (Col. 3:17). Whether, then, you eat or drink or whatever you do, do all to the glory of God (1 Cor. 10:31). Strive to say as Paul wrote, “I count all things to be loss in view of the surpassing value of knowing Christ Jesus, my Lord, for whom I have suffered the loss of all things and count them but σκύβαλον (garbage, filth, animal excrement) in order that I may gain Christ” (Phil. 3:8).