How do you live the Christian life? 

That may seem like a rhetorical question. But it is not. It is a serious question.  

Most Christians don’t really know how to live the Christian life. They just figure that they’ll try their best.  

David was trying his best when he attempted to move the Ark of the Covenant to Jerusalem in a way contrary to God’s command. He meant well. But Uzzah died because David tried to do God’s work in the wrong way.  

The Christian life has often been called “a faith walk.” But it is not clear to most Christians what a faith walk is.  

The purpose of First John is that his readers would continue to have fellowship with the Lord Jesus Christ (1 John 1:3-4). Throughout the letter, he gives various keys to living the Christian life. In 1 John 4:20–5:15, John gives three keys to living the Christian life. The first is found in 4:20–5:3a. It is this: 

Key #1: Realize That Loving Our Spiritual Brothers and Sisters Is the Measure of Our Love for God.

John wants us to know how to accurately gauge whether we are pleasing God. To do that, John must give us a way to determine whether we love God.  

We cannot love God, whom we have not seen, unless we love our Christian brothers and sisters, whom we do see (4:20).  

We are commanded by God to love our Christian brothers and sisters (4:21). This is what pleases Him. This is what He wants us to do to show our love for Him.  

And who is that? John answers that in the next verse (5:1, which should be 4:22). Our brothers and sisters are the ones who believe Jesus is the Christ.  

This is a key verse. It is much misunderstood. It doesn’t mean that we believe Jesus is the Messiah, though He is. It means what John 11:25-27 shows—that He is the Guarantor of everlasting life to all who believe in Him.  

To believe that Jesus is the Christ is to believe that He guarantees eternal life to the believer (cf. John 11:25-27; 20:30-31; see also John 4:10-26).  

So, the one we are to love is the one who professes to believe that simply by faith in Jesus, he is eternally secure.  

But what if a brother or sister is not living as he or she should? We are still to love them.  

Of course, we are to love unbelievers as well. But the priority is always in Scripture on loving our fellow believers. Compare Gal 6:10 and “especially those of the household of faith.”  

The issue in 1 John 5:2 is not our feelings or our emotions toward our fellow believers. It is our actions and our prayers. 

It is also, of course, our desire to see God work in and through them. As we live out the Christian life before them, we model what we desire to see God do for them.  

In the first part of verse 3, John says that loving God means keeping His commandments. “The love of God” here refers not to His love for us (subjective genitive), but to our love for Him (objective genitive) as verse 2 made quite clear.  

Here is the logic behind what John is saying in 4:20-5:3a. 

Major Premise: I claim to love God the Father who commanded me to love my fellow Christians. 

Minor Premise: I do not love my fellow Christians.  

Conclusion: My claim to love God is a false claim. 

Imagine you are in an earthly family. You claim to love your father, who is no longer with us.  

Yet before your dad died, he commanded you to take care of your brother.  

Well, you no longer see your dad. But you claim you love him dearly. 

Yet you do not lift a finger to help your brother who is in need.  

Nor do you set a good example for your younger brother. You are not living in a way that would please your dad.  

You may think that you love your father because you speak well of him or because you have a warm feeling for him in your heart. But if you don’t do what is dear to his heart, how can your claim to love him be true?  

Now compare this to God the Father.  

We have never seen Him. 

But we do see His children.   

The fact that you speak well of God is no excuse. The fact that you have warm feelings for God does not mean you love God. No matter how sincerely you sing, you do not love God unless you love His children, your brothers and sisters in Christ.  

Keeping grace in focus greatly aids us in loving God by loving His children.