It's a duty of every Christian.
It's just like a student having to go to school every day, an
employee having to report work every day or a husband/wife having
to go home for dinner with the spouse.
It's a responsibility. It's an obligation.
There have been Christians who give excuses and would say this "I
read bible and I worship God from my heart. Thus, I don't need to
be physically present in Church"
Imagine if we put these words in another context. Imagine a married
person says this "I wear my wedding ring every day and I love my
wife from the bottom of my heart. Thus, I don't need to be there
physically to give her emotional support."
Or a student saying this "I know study is important. I go through
the textbooks every day. Thus, I don't need to go to school
everyday.