After OC County GOP official Marilyn Davenport sent out a picture of President Obama as part of a family of chimpanzees, she apologized, saying, "at the time I received and forwarded the email, I didn't stop to think about the historic implications and other examples of how this could be offensive."
No, the problem is not that you didn't stop and think before sending it. The problem is that you were not offended when you first saw it. The problem is that if you really recognized it was offensive, you wouldn't have to stop and think about it. You wouldn't have to have that self-conversation of, hmm would it be wrong to send this along? You would have written back to whoever sent it to you and scolded them for sending you such offensive material.
But you didn't do that. You were, as you say, "an imperfect Christian."
Thanks for your guarantee that you won't "repeat this error." That's mighty big of you.