And forgive us our debts, As we forgive our debtors. Matthew 6:12
We are called to confess every sin we commit to God.
Not every sin against another person should be confessed to that person. If I have sinned against another person and they know about it, I must by all means seek the offended party’s forgiveness.
However, if I have sinned in my heart without the person ever knowing about it, telling them could be detrimental. For example (and I’ve told this story before), a man I barely knew approached me after I preached at a conference. He proceeded to tell me that he never liked me and harbored bitterness in his heart toward me for years. He asked for my forgiveness. Of course, I forgave him, but honestly, even if he felt better about asking for my forgiveness, I didn’t!
There is a saying: “The circle of confession should be no larger than the circle of sin.” Surely there are exceptions, but I believe it is generally true.
Even when one speaks unkindly about another person, asking forgiveness from the one spoken to is in order. But in some cases it may make matters worse by confessing the sin to the one who was spoken about (if he or she has no knowledge and likely will never know about the offense).
There is no one-size-fits-all in such matters. That is why we must seek the Lord’s will in each case, with the goal to make things better, not worse.