Many times we make mistakes due to our lack of knowledge or wrong information. I see nothing wrong with that. But after making a mistake, if you do it again without learning from it, it is a sin. I think that's what the OP meant. I'm the one who always needs to get this idea out of our minds. If someone points out a mistake, it should be corrected politely.
Making mistakes is normal since no one is perfect, but making corrections is the important thing here. If you fail to learn from your mistakes, then you are not ready to learn, and you keep repeating that same mistake.
One thing I like with this forum is that, once you make a single mistake, you will be corrected immediately, but some newbies do take it as criticism and take it personal instead of taking the important message from any comment and leaving everything, Some of them tends to reply and use emotion towards any rude comment from some exiting members of the forum. I will want all the incoming and existing members to know and remember that this is a general and public forum that contains members from different locations across the world, and since we know that we have different mode of approach, lets just take anything important and leave the rest. Besides, learning through criticism is easy and you will learn fast. Therefore, let's keep emotions aside and learn.