Can we say and prove that the 12 Imams were divinely appointed? If so, then why cannot other sects, who deny this matter, be called Kafir as a result of rejecting this divine appointment?
Bismillah
By testifying that there is no God but Allah and the Muhammad (saw) is the messenger of Allah a person enters the fold of Islam and cannot be classified as a Kafir, even if they do not agree with the issue of Imamah despite clear proofs and evidence.
May you always be successful