Once, in perplexity, people asked Jesus, “What are we supposed to do?” (John 6:28). The Second Reading raises this question for us too. 

The Second Reading says that if you don’t keep God’s commandments but say that you know the Lord, you are a liar. 

Being a liar is bad enough. But the Second Reading also says that if you don’t keep the Lord’s commandments, you don’t know the Lord.

That is the worst, isn’t it? Especially because the test for whether or not you know the Lord is not whether you have fervent prayer or sweet religious experience. No, the test is just whether you keep the Lord’s commandments. That is why you lie if you don’t keep the Lord’s commandments but still try to tell yourself and others that you know the Lord.

In another passage, this same Epistle (1John 1:6-8) claims that if you say you have no sin, you are a liar, too. 

And now we have a real puzzle, don’t we? To avoid the sin of lying, you have to confess that you do sinful things. But then you are confessing that you aren’t keeping the Lord’s commandments, aren’t you? And in that case, you are a liar, and you don’t know the Lord.

Well, then, what are we supposed to do?

The answer is in what Jesus told the people when they asked him that very question. Jesus said, “Believe in the one whom God has sent.” (John 6:29)

Notice that this is a command.

And here is what it means. We can tell the truth: we are sinful. But it doesn’t follow that we don’t keep God’s commandments. If we believe that Jesus is the Savior, sent by God to save us from our sins, then, sinful as we are, we are in fact keeping the commandment the Lord gave the people when they asked him what they were supposed to do. 

And if we keep his command, then it is also true that we know him. We know him as the Christ, sent by God to save us from our sins.

It can be true then both that we are sinful and that we keep the commandment of the Lord if we believe that he will save us from our sinfulness.

So this is what we are supposed to do: know him.