What is the ruling on being ignorant about monotheism? Could there be an excuse?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

There is no excuse for people who have been informed about Islamic monotheism and for whom certain issues have been made clear. The same applies to those who live in Muslim countries and listen to Islamic speeches, preaching, the words of Allaah The Almighty, and the Sunnah of the Prophet, sallaallaahu ‘alayhi wa sallam . The Da‘wah (call) to Allaah The Almighty has reached them, so they could not plead ignorance and be excused thereby.

On the other hand, Muslims who live in non-Muslim countries or in a desert or remote areas and do not have access to scholars are considered ignorant and therefore, they would be excused for being ignorant about some matters. The evidence that  only those who are informed would be punished  is what Allaah The Almighty Says (which means):

•  {And this Quran was revealed to me that I may warn you thereby and whomever it reaches.} [Quran 6:19]

•  {And never would We punish until We sent a messenger.} [Quran 17:15]

It was narrated on the authority of Abu Hurayrah that the Prophet, sallallaahu ‘alayhi wa sallam, swore that any Christian or Jew who heard of him, sallallaahu ‘alayhi wa sallam, and died without believing he was the Messenger of Allaah would enter Hell. [Muslim]

Allaah Knows best.