Why is astrology considered a sin in Christianity?

I am new to Christianity and I do not have anyone in real life to ask my questions. In my country, the dominant religion promotes astrology a lot. But I have heard that it is a sin in Christianity. **But, I do not know the reason why?** I was very stressed lately and spent a lot of money on astrologers. Never got any reasonable answers. I have been in serious trouble earlier in life due to guidance by astrologers. The origins of astrology are extremely dubious! Why it is a sin in Christianity? What is the rationale behind it?