Why is fortune-telling among the Orthodox considered a sin?
A person should not know what is in store for him, otherwise he will turn off the right path, he may start doing unrighteous deeds, and fall to the bottom. In addition, people are gullible, they easily pass from God to evil spirits. A person should live the way he lives, turn to God for help, and not believe imaginary fortune-tellers.
Probably, the issue is not exactly covered here. The fact is that Buddhism is much deeper and it is also divided into those who observe all 108 commandments, and those who no longer believe in samsara, but in the paradise-hell model. And our Orthodoxy is a special kind of faith. Accordingly, hence the different approach to fortune telling. Is fortune telling a sin? Yes. Because a person climbs into those areas of darkness and darkness, from where he may not get out on his own. Although the results of fortune telling are sometimes more than impressive, they should not be engaged in. For, as it is said, "And the hair will not fall from the head of the son of man Without my will" - if you believe, does it make sense for you to know what will happen in the future if it happens by the intention of the Lord? Fortune-telling in this case is similar to how loving children hired a bloodhound detective for their beloved parents, arguing that "they are just curious to know."
When fortune-telling, a person can turn to evil forces to obtain a result. Where do people get their information from? That is why, I think, fortune-telling is considered a sin. Upon receiving the result of fortune-telling, a person changes his behavior, he already becomes different.
Fortune-telling is a sin, since it is an occupation of the occult. It is believed that occultism is communication with demons. It is a sin that separates us from God and makes us related to the Devil.
Fortune-telling is considered a sin not only from the point of view of Orthodoxy, but also from the Bible. Let some say that they have divined the truth, this is what is written in Acts 16: 16-18: “We met a certain servant in whom there was a spirit, demon diviner". This is where it is specifically written: Deuteronomy 18: 10-12.