What is the heart's rejection of disbelief, and is it merely knowing of its bearer's doom and having aversion to that?

Denouncing evil with the heart is to detest it, and this is its place when one is unable to denounce it with the hand or the tongue, along with the obligation to leave the place of evil if possible; otherwise, the Muslim incurs sin. Hating disbelief and not being pleased with it necessitates knowledge of its practitioner's perdition. The denouncement of disbelief by the heart does not necessitate disbelief for the Muslim as long as he detests it in his heart.