"This is His commandment, that we believe in the name of His Son Jesus Christ, and love one another, just as He commanded us. The one who keeps His commandments abides in Him, and He in him. We know by this that He abides in us, by the Spirit whom He has given us." (1 John 3:23-24)Someone once asked Jesus what was the greatest of all the commandments of God. Jesus replied, "'You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.' This is the great and foremost commandment. The second is like it, 'You shall love your neighbor as yourself.' On these two commandments depend the whole Law and the Prophets." (Matthew 22:37-40) Here John repeats these words of Jesus substituting belief for love. Belief is often the starting point of love. If we believe Jesus and the things He spoke and promised, then we will begin finding ourselves loving Him for who He is and what He has done for us. When Jesus forgave the sinful woman at dinner, much to the displeasure of the Pharisees, He said, "For this reason I say to you, her sins, which are many, have been forgiven, for she loved much; but he who is forgiven little, loves little." (Luke 7:47) Because of their unbelief, the Pharisees were unable to receive of His forgiveness or to find love in their hearts for Him for what He had to offer them. Their unbelief rendered their love for God dead.
The second part of the commandment of God is that we should love one another. This kind of love is a love of action. It is more than words or sentiment, but it is deeds and requires choosing for others rather than ourselves. It is a love that distracts us from our own selfish needs and wants to the needs and cares of other people. Some may ask, "How can you truly love God?" Jesus responded, "Truly I say to you, to the extent that you did not do it to one of the least of these, you did not do it to Me." (Matthew 25:45)
Furthermore, John says that we should be careful to keep these commandments of God. The Greek word for "keep" means to "guard" and has with it the connotation of a military deployment to keep a city or nation safe and secure. Our lives do not automatically tend towards keeping the commandments of God. It is something we must give effort to and be watchful over. We must ever be diligent to remain firm in our belief and constant in our love. The commandments of God take doing, not just hoping or assuming.
These commandments, believing in God and loving others, is the key to abiding in God. Some believe that we abide in God when we abide in prayer, worship, fasting, or some other individual form or spiritual devotion. However, John says that we abide in God when we love other people. There is a time for prayer but there is also a time for action. How can we expect to abide in God if we seek to withdraw ourselves away from the very people we were meant to love? I think this misconception was at the heart of what was wrong with the monastic movements in the centuries gone by. If we are to abide in Christ, then we must engage the world and those in it.
Finally, John reminds us that God abiding in us is not a mere concept or poetical wish. God abides in us through His very real and present Spirit. God's spirit is more than an impersonal force, more than a thought or idea, more than power or energy, it is the true and abiding presence of God in our lives. He abides in us by His person through the Spirit. In our abiding in God we must never forget nor neglect His abiding in us through His spirit.