What is the condition of those who died before hearing the call to Islam or if the call to Islam that they have heard has been delivered incorrectly?

Well-established Muslim scholars have affirmed that an important component of a valid call to Islam is that it is communicated in a correct and undistorted form. If it is not, then the recipients of this call may not be blamed for not being convinced by it.

There are still [a few] people who have never heard the call to Islam like notably those living in caves, jungles, and remote islands, with next to no communication with the wider world, despite the recent explosion in media technologies, and [improvement in] travel. Of course, anyone who hears of the

Messenger who came with a religion called Islam should attempt to find out about it, if possible. However, if he does not hear about it, or if he hears about it but is unable to find out about it [through reliable information], then he is to be excused. This is the opinion of the scholars of Islam. A condition was set by these scholars to the effect that, if it is to be treated as valid, the call to Islam must be complete [and not include falsities]. If, in contrast, the Muslim message is relayed in an imperfect form, its recipients should not be blamed for not being convinced by it. This was stated in Imam al-Ghazali’s book, The Line of Demarcation between Islam and Heresy. There, he [al-Ghazali] mentioned that, in his day, most Christians of Roman and Turkish origins would be saved because they had not, as yet, received the message of Islam. Ghazali wrote the following:

I would even say that those who receive the message of the Prophet (upon him be peace) in an imperfect form, or who are told that a liar and swindler by the name of Muhammad has falsely claimed to be a Prophet, will both be judged according to the same criteria. In my opinion, they will be saved. The remaining nations, who deny the message of the Prophet (upon him be peace), after hearing many times of his actions, character, and miracles – the greatest of which is the Holy Qur’an – and still refuse to investigate this [the Prophet’s] message are the non-believers.

Accordingly, those who have not received the message, or who received it in imperfect form, or who heard it correctly and, thereafter, dedicated themselves towards understanding it are, it is be hoped, saved from an eternity in Hellfire.

According to the great Islamic scholar, Ibn Taymiyyah:
Based on specific historical moments and particular geographical locations, a man will be rewarded with the little that he possesses in terms of faith. God Almighty forgives those with an excuse and will not forgive those who do not have an excuse. This is illustrated by the following hadith. “There will come a time when people do not recognize [the obligation to perform] their prayers (salah), fasting (siyam), pilgrimage (hajj). The exceptions to this will be the elderly who will say that they once saw their fathers perform the shahadah [i.e. bear witness that there is no God, but God, and that Muhammad is His Messenger – the testimony of faith in Islam]”. Then, Huzaifah ibn al-Yaman was asked, “Is shahadah sufficient for their salvation?” He replied, “It saves them from Hellfire”. And God knows best.