The 84,000 Dhamma doors are a metaphor to basically state that there are innumerable paths to enlightenment. In the Mahayana it is referred to as doors and in the Pali Canon it is referred to as the 84,000 teachings (Khuddaka Nikaya, Theragatha 1024). This is a representative teaching to the Buddha’s tolerance for other religions. Anyone following any religion who is basically a good, moral person is assured to reach that religion’s goal, which is typically heaven. In the Buddhist cosmology there are several heavenly realms all of which are attainable by members of any religion.
(from KN, Theragatha 1024)