What is the way to know the truth and follow the correct Sunnah, given the mosque imam's warning against some sheikhs and satellite channels, and some people's questioning of your website's reliability?

To know the answer, please refer to Fatwa no. 132563 and what it references. To learn about the Fatwa Center, its mechanism of operation, and its methodology, please refer to Fatwa no. 30598 and this link: https://www.islamweb.net/ar/fatwa/index.php?page=aboutfatwa.