The assembly, then, is the place for hearing God's Word and for offering Him promised praise.
If I hear one more person say, "God is everywhere. Why should I have to go to church, to any building, to pray to Him?" I will be able to restore all the pipe organs.
As the "pillar and foundation of truth" (1 Tim 3:15), the Church is charged to call people out from the hinterlands of deception and denial, into Reality.
Sure, we can and should pray wherever we are; but God calls us from the security of our inner room, our echo chamber, into His sacred assembly. He calls us out of our self-constructed prisons into "the glorious freedom of the children of God" (Rom 8:21).
At heart the Church is a reconciled and reconciling communion of believers. At times I may fail to act as a member of that communion, so I need to be called out for those failures to act. When I'm by myself, I don't get that kind of caring accountability. Chances are, I don't really want it.