Akmal wrote: ” I wanted to ask if phenomena such as spirit possession being done either willingly by a spirit/mara/yaksa/demon or through black magic is effective on Ariyas or those with Noble attainments.”
Relevant basic ideas are discussed in the post, “What Does Buddha Dhamma Say about Creator, Satan, Angels, and Demons?“.
Mara is different from other “bad beings”. Mara is a deva in the highest deva realm. He wants people to engage in moral activities and to be reborn as devas. But he is opposed to Buddha and his disciples because he thinks attaining Nibbana is bad.
– However, other bad beings who are in either the lower realms or the first deva realm tend to try to direct people to do “bad things”.
Neither type can harm true disciples of the Buddha, especially those who have attained magga phala.
Now, PEOPLE doing “black magic” is a different topic. Yes. I know that in Sri Lanka (especially in the old days), some people used to do certain things (“black magic”) to try to harm their enemies. But that practice losing ground now, because people are more informed.
– I do not really know whether those practices are effective or not.
– However, just like good thoughts can positively affect other people, bad thoughts can negatively affect targeted people. That is especially true if the “targeted person” has bad character qualities.
The bottom line is that if one lives a moral life and follow the Noble Path, one cannot be influenced by such external forces. It is those with bad character and weak minds who can be affected.
– People in Asian Buddhist countries also play “sutta chantings” in their houses regularly. I remember that it was done every morning while getting ready for school/work.
– That could have an effect of “keeping bad beings away” too. It is also conducive to a calm mindset; see, “Buddhist Chanting“.
One should also keep one’s house/environment clean. That can have a significant effect on one’s mindset. A simple, moral life goes together with simple, clean environment.
– Just like bad character qualities tend to attract bad friends, unclean environment will attract flies, cockroaches, mice, etc. and make that environment even more unhealthy.
– If one can visit a temple especially in Asian countries, one can clearly see that it is a simple and clean environment for a positive mindset, and that it is conducive to contemplation (bhavana).