Is it permissible to believe in the disbelief of a person who exhibits outward signs of disbelief, or is it obligatory to refrain from passing judgment on him due to the inability to ascertain what is in his heart?

Whoever manifests disbelief verbally or actively is judged to be a disbeliever, unless he is under duress that is considered valid. The fact that he conceals something contrary to what he reveals does not prevent him from being judged a disbeliever. The scholars have reached a consensus on this. So, whoever manifests disbelief in agreement with the polytheists, out of fear or desire for worldly gain, is a disbeliever like them, even if he dislikes their religion and loves Islam, except for the one who is compelled to utter disbelief while his heart is content with faith.