Is Not Attending Church Service Every Sunday Such A Big Sin?

So today(Sunday) I decided to stay at home because of yesterday's wedding I attended. Not that I don't go to church but I came back home yesterday feeling very tired, even till this morning.

A neighbour saw me this morning and was like "Bros, you no go church today?" I tried to make him understand why but he kept on telling me how it's wrong not to go to church and stuff.

So the question on my mind today is, why do people tag others who "miss" Sunday service as sinners?

source http://www.nairaland.com/6256993/not-attending-church-every-sunday