I have some disagreement about this. Since our thoughts are a mixture of our conscious decisions and cultural context there are times when offensive thoughts bubble up. What make you a good person is not acting on this offensive thoughts, noting them and consciously attempting to change them. So you are correct to change your thinking but its a process and no one is perfect. As you change them they lessen but we all have times when our thoughts aren't as enlightened as we want to be.

What if your thinking is correct, but the truth hurts?