There were things that Yin Ruobing indeed didn't tell Jiang Yi and wouldn't tell him either. Like the things of the Divine Temple. These were secrets that only the members of the Nine Thearchs Clans were qualified to know.
The Divine Temple was indeed very dangerous, and in the first 29 days of the opening, the mountain range would be filled with astral winds which were 100 times stronger than the outside. No one would be able to enter, and the astral winds would only get lesser on the final day. Everyone would be able to enter the central valley as they pleased.
After entering the valley, it would be absolutely safe. Of course… the interior of the Divine Temple was even more dangerous. Those without the information provided by the previous clan members that entered would never dare to enter the Divine Temple.