The Sun and Moon Divine Sect's worship ceremony is held on the first day of every month, contrasting with the Divine Sacrifice that takes place once every three years. The monthly worship, on the first day, is relatively loose.
It's not mandatory to attend, rather casual, but this casualness applies only to martial artists who are qualified to worship.
Over ninety-nine percent of martial artists in the Sun and Moon Divine Sect wish to worship, but do not have the qualifications.
Being loose about whether to worship does not mean one can be negligent during the ceremony; on the contrary, each worship, whether attended by many or few, is very solemn.
Due to his previous trips to the Immortal Realm Spiritual Veins for cultivation, Ye Zhen had never had the chance to worship, and this time just happened to coincide, so he certainly couldn't miss it.
The idol of the Sun and Moon Divine Sect was a great mystery in Ye Zhen's heart.