Apologize for three things that Christians have often got wrong. Your apologies should be directed towards those who don’t view themselves as part of the Christian community. Alternatively, apologize for things you personally have done wrong towards those outside of the church.
Confessing on behalf of a group is tricky, especially when one isn't appointed to do so. It'd be easy for me to drift into a list of my top three peeves about the church under the cloak of apology. On the other hand, it's also easy just to hide out and never enter the realm of corporate confession because of that trickiness, keeping junk that should simply be brought out into the open under wraps. I don't know that I can "keep it between the ditches" of either danger, but in hopes of doing so, I'm going to target my apologies to things I know I've been a part of, either presently or in the past.
I'm sorry for judging too quickly. This is my own failing and probably doesn't have a direct connection to my being Christian—it seems likely that I'd do it regardless. But my desire to "get it" and have everything/one figured out can make me miss so much. Perhaps worse, others can be distracted by my opinions and get sidetracked from the truth of Christ. Paul had it right: "For I decided to know nothing among you except Jesus Christ and him crucified" (1 Corinthians 2:2). The rest is details and needs to become less.
I'm sorry for acting as if the gospel is anything less than "the words of eternal life" (John 6:68). Sometimes I downplay it because I'm afraid others will think less of me or it's somehow disrespectful in case someone believes something else (or nothing else). Too often I treat the gospel like a job, hobby, or "belief system," dusting it off only when I think it will get me something (approval, esteem, etc.) and only in doses that I think will be easily accepted. Even internally, I too often try to navigate by my own resources, and that shortchanges me and everyone I interact with from the grace and power God wants to bring to bear in and through my life.
I'm sorry for not being willing to say "I don't know" more readily and often. This is connected to the first apology, but is big enough to deserve its own space. Christians are exhorted in Scripture by Peter:
…in your hearts honor Christ the Lord as holy, always being prepared to make a defense to anyone who asks you for a reason for the hope that is in you; yet do it with gentleness and respect, having a good conscience, so that, when you are slandered, those who revile your good behavior in Christ may be put to shame.
What I've often forgotten is that this doesn't mean having an answer for everything (debating until one party runs out of answers is a ridiculous measure for truth). In fact, because of the overriding importance of the gospel, the rest of life may well have more questions than answers. Sometimes "understanding" is just another way for me to feel in control. The gospel calls me out of that, into a place where it's OK for me to admit when I don't know something, because it's not all riding on me and my answers.