In the Second Reading, Paul warns people not to grieve the Holy Spirit of God. It is a sad thing to grieve your mother or your best friend. It is really dreadful to grieve God himself. How does a person manage to do such a lamentable thing?
You grieve God when you engage in malice, Paul says. Now malice is the opposite of love. To love someone is to want the good for him and to want to be united with him, too. So you can be malicious by refusing either of these desires of love. If you want what is bad for another person, or if you utterly reject another person, you are malicious with regard to him.
Bitterness is on Paul’s list of ways to grieve God, too. A bitter drink is one that has no sweetness in it; it just sets the drinker’s teeth on edge. Your heart and mind are bitter if you are focused largely on the bad in things, and that bad-tempered focus of yours sets everybody else on edge as they try to tiptoe around you. You can’t want the good for others if all you can see is the bad in them. And you can’t want to be united with them either if your bitterness blocks joy in you.
If you revile others, if you are bitter, you are malicious; and when you are malicious, you are opposed to love. But God is love, and it isn’t possible for there to be union between God and what is opposed to God.
Your malice grieves God, then, because he has lost you when you are malicious; and, for God, your loss is worth grieving.
It’s a sobering thought to be so loved, isn’t it?