What is the destiny of those who heard about Islam but know nothing about it, and Christians like Mother Teresa, and atheists who were forced into atheism, and Hindus and Buddhists, and monotheistic Jews?

Allah does not punish anyone until proof is established against them, by the reception of Islam and the ability to learn about it. The establishment of proof varies according to circumstances, times, and individuals. Whoever dies as a disbeliever after proof has been established against them will be among the people of Hellfire, and their good deeds will not benefit them due to their disbelief. As for the disbeliever who did good in this world, they will be recompensed for it therein, and they will have no good deeds in the Hereafter. As for whoever dies upon other than Islam and the call did not reach them adequately, their ultimate fate is a matter of scholarly disagreement. Some scholars decisively excuse them, based on His (the Most High) saying: "And never would We punish until We have sent a messenger." Others say that they will be tested on the Day of Resurrection, and this latter opinion is the one many scholars have supported.