why minor sin and why kufr

Selam alejkum. I know it is weird but people with ocd sometimes have extreme intelligence to the point that I won the third place in national olympiad of mathematics but sometimes they don’t understand things that are simpler than 1+2=3. I remember once making this kind of question on chatislam and the response was: how dare you say those things about sahabah?! Are you mentally insane? With sahabah I mean both men and women because many sahabah have been women.(sahabah are those that have seen or met the messenger) Remember that he has no intention of making fun of them or disrespecting them or lowering their esteem. But he intentionally imagines them in that state without feeling anything about them. In other words not a single sexual feeling or offensive feeling passes his body, just like not a single sexual or offensive feeling passes your body when you imagine a tree, mountain, or umbrella. I want to know all the elements that cause it to be kufr. Is it entirely a matter of zina of the heart that is done with a noble and sacred individual?  Is it entirely a matter of disrespect that is shown toward a noble and sacred figure? Is it entirely a matter that you are not giving them the proper esteem? Imagining nude a woman is minor sin.in big contrast imagining nude a sahabah is kufr. I want to know all the elements that cause it to be kufr in the case of the sahabah. Is it zina of heart that is done with a noble and sacred figure? Is it lack of respect that is shown towards a sacred figure? Why? Aren’t they both humans at the end of the day? Please explain every detail that causes it to be kufr.

please sent your answer to tavolinekarrige@gmail.com. It is not a dream but it is a very important fiqh issue and i am begging for your personal opinion