What is meant by shirk being an insult to Allah Almighty, and does it include major and minor shirk, and does one who commits minor shirk, while believing it to be an insult to Allah, become a disbeliever?

Shirk is a defamation and a diminishment of Allah the Almighty, because it assigns a rival to Allah to whom worship is directed. Major shirk diminishes Allah and offends Him. As for the monotheist, he exonerates Allah even if he commits sins or minor shirk.