Why is resentment the first topic of Step Four? The first inventory question of Step Four is on page 67, when we are asked to look for our mistakes. Before then, we're not taking moral inventory; we're cataloguing our resentments, seeing through their folly, and eliminating them using forgiveness. Why?
When I see you as bad as opposed to mistaken, that becomes my fixation. This is not an isolated observation but an element in a whole worldview, in which I am suffering because my plans have been thwarted, and it's your fault. In other words, the flipside of resenting you is perceiving myself to be innocent. Furthermore, if you're bad as opposed to mistaken, any otherwise immoral actions of mine are neutralised, since you deserve punishment, and my behaviour is the punishment. If you're bad, I can do no wrong.
It's therefore impossible to look squarely at my wrongs until yours are reclassified as neutral actions or, at the very most, mistakes. Error calls for correction not punishment, and the immorality of my own punishing conduct is then thrown into stark relief.
If you're struggling to come with answers to the page 67 questions about mistakes, and so forth, the chances are that there is unforgiveness present, which is part of a larger structure blocking true self-examination. Until forgiveness takes place, no progress can be made.