Jesus never said “I’m sorry.” Sure, when he was being crucified, he cried out: “Father, forgive them, for they do not know what they are doing (NIV).” But technically he was apologizing on behalf of others and not for a sin he actually committed.
Apologizing is one of the only Christian virtues Jesus didn’t do himself.
Maybe this is why Christians rarely hear sermons or teachings about apologizing to non-Christians. Mainstream Christian culture teaches the opposite: believers are always right. The inner-circle perception is that Christians don’t make mistakes — only non-Christians do.
As children we’re taught to apologize for lying, stealing, hitting our little brother, budging in line, cheating on a test, and swearing (among other things). Most people with common decency apologize to each other for these trivial wrongdoings, but when it comes to spiritual things — especially on a widespread and corporate level — Christians rarely apologize to people beyond their faith.