On Rosh Hashanah we open the gates of the year, so that God may enter.
To do so, everything needs to be in its place.
The world must be worthy of receiving God.
This is the meaning of our collective presence at the synagogue.
By going there on Rosh Hashanah, Jews say, "Last year was more or less all right. We behaved more or less acceptably. But we want to continue. Grant us one more year."
In a way, the children of Israel go to the synagogue to reiterate their pledge of allegiance to their King and, and beyond their shortcomings and expectations, to express the sole wish that God will, in turn, accept the crown from His people.
–Rabbi Adin Steinsaltz
From The Seven Lights by Rabbi Adin Steinsaltz