Question: When Amitabha Buddha appears to Pure Land practitioners who are on the brink of death, how can they be sure it is not a demon?
Answer: If a Zen follower is not meditating on the Buddha, and yet Buddha suddenly appears unexpectedly, this is called a demon (delusion). A Pure Land practitioner sees the Buddha while focusing on the Buddha. Thus in his case, cause and effect coincide and his mind is in unison with that of the Buddhas. The appearance of the Buddha is therefore not a demon. There is no need to worry about this. (From p.94 of ‘Mind-Seal of the Buddhas’ by Patriarch Ou-I)
Another Answer: If we are sincerely mindful of Amitabha Buddha (Amituofo) with right faith, aspiration and understanding, the one who appears cannot be a demon, especially since the mindfulness of Buddha itself protects one from demons, while all Buddhas of the six directions bless the practitioner. This is recorded in the Amitabha Sutra. As taught by the Buddha –
… why do you think this teaching is called ‘the Sutra of Protection by All Buddhas’? Shariputra, all good men and women who hear this sutra and hold fast to it and also those who hear the names of those Buddhas are protected by all the Buddhas…
If visions of other ‘enlightened beings’ (Buddhas and Bodhisattvas) appear despite not being mindful of them, one should continue being mindful of Amitabha Buddha till he appears as other visions might be manifested from demons.
Q: Is it alright to also chant ‘Om Mani Padme Hung’ and/or ‘Namo Guanshiyin Pusa’ while chanting Amituofo’s name at other times?
A: It’s alright, as chanting the above can also be for birth in Pure Land. But it’s good to have one main practice too, the one that we are most used to. You can think of it like riding the bike you are most familiar with versus riding others’. The one you ride the most should be your main vehicle – the one that would most efficiently lead you to your destination with ease and security.
Should We Focus on All Buddhas & Bodhisattvas?