Is it possible to be repentant and forgiven for something without telling anyone you did it? Or is confession to another person a necessity?

Well, the short answer is that confession to another person is not an absolute necessity. If you were to have a lustful thought and then a heart attack, you wouldn't go to hell if you were born again.

I think a person who is asking this question may be operating under a kind of mechanical notion of the way repentance towards God and confession of our sins towards others works. And I would like to relieve that person of that mechanical notion.

But really more helpful might be to ask, What is the role of confession to other people? When should you do it, and why would that be helpful?

James 5:16 is the key text there: "Confess your sins to one another ... that you may be healed." So something really valuable happens when we confess our sins to one another.

If you sin against another, the Bible is pretty clear that you shouldn't first go to the altar, but first go and get it right with your brother before you go to the altar (Matthew 5:23-24). So confession is crucial at that point to another person.

But even there I don't want to say it's absolute, because my guess is that the thief on the cross had offended so many and hurt so many people when he became a Christian and he had no time to make any of it up. He went straight to heaven half an hour later, as Jesus said: "Today you will be with me in paradise."

So it is not an absolute necessity, but it is very healing for relationships.

We want two things to happen in repentance:

1. We want the air cleared with us and God. So we say, "God, I've sinned. I'm sorry. Apply to me afresh the blood of Jesus," and we enjoy that fresh fellowship and forgiveness.
2. And we want this horizontal relationship to be clean and clear and open, because so much pain comes into life, and even physical maladies come into life, when we are keeping our sins inside. "I kept my sin in and my bones wasted away" (Psalm 32:3).

So there is a healing that comes at the horizontal level as well as the vertical when we confess our sins to one another.