When are sins of the heart activated the most? I mean, is it a must for you to be commiting outer sins in order for the inner sins to be activated or it is possible for the inner sins like pride, jealousy to be activated even when you are reading Quran? if you cannot answer all, at least answer: can inner sins be activated even during reading Quran?This point is most important because it clarifies all. Outer sins are sins that are committed with hands, tongue, eyes or any other part of body. Inner sins are sins of heart you may commit without moving any part of your body. Example: You can hate, love, unjustly without moving your body or tongue. Loving sins, or evil things are among the most widespread illnesses of heart. You can have all those illnesses of heart described by scholars like Ibn tajmija even without moving your fingers or tongue by one millimeter. Question. Is it a must to watch haram things or do haram for these illnesses of heart to be activated and written as sins by angels.
As I understand your question, you are asking whether wrong thoughts/negative feelings (such as jealousy, anger, hate etc) are caused only by sinful actions.
The answer in my humble opinion is no. Firstly, only Allah (SWT) knows the true inner thoughts of a person and what one may perceive as a bad thought ("inner sin") may turn out to be a positive thing. Secondly, in the Quran (for example Chapter 113,114) other agencies are mentioned, such as whispers of shaytan who puts evil in the hearts of men.
Hope this answers your question.