When priests tell people about future sufferings and make them do rituals, aren’t they acting like hooligans who threaten people to extort money?
Not necessarily. They could be acting like doctors who alert patients about how they will become sick in future if they don’t take treatment now. Their statements could be warnings, not threats. To understand the difference, we need to ask: who is causing the suffering? In the case of extortion threats, the hooligans are themselves the cause; they will inflict sufferings on those who don’t give money. In the case of sicknesses, the doctors are the helpers in preventing the sufferings caused by something else like germs.
Similarly, the Vedic scriptures inform us that various sufferings come upon us due to the law of karma. This law is basically an expansion of the law of cause and effect that we intuitively accept in our daily life. All of us carry past karmic infections that will cause us to suffer in due course of time. An educated eye is needed to see how certain symptoms are precursors to future problems. The difference between seeing the symptoms of physical diseases and the signs of karmic consequences is just the difference in the kind of education needed.
Certain religious ceremonies help us atone for what we have done in the past. At the same time, not all religious rituals are necessary, just as not all medical prescriptions are necessary. Some doctors may give unnecessary prescriptions to inflate their earning and so may some priests. Just as we need to educate ourselves and choose our doctors carefully, so too with priests.