The Doctrine of Attendance...a misguided application of a spiritual truth in today's churches...
And when he was demanded of the Pharisees, when the kingdom of God should come, he answered them and said, The kingdom of God cometh not with observation:  Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you. Luke 17:20-21
The moment this verse is brought up within the context of a conversation about the doctrine of attendance, as I call it, feathers are immediately ruffled.
I say this based on my past experiences with this along with the many churches I have attended where they would constantly goad attendees to make sure they are at as many of the services throughout any given week as they possibly can. They push all of this essentially based off of one key scripture where in Hebrews chapter 10 verse 25 it states " Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day." They do this with a emphasis on attendance over ensuring that the attendance should be only for genuine believers. They consistently extend this to everyone, believers or not and they tend to emphasize that for the members of the church attendance is pretty much expected.
Yes, fellowship is a spiritual truth and a necessity for all believers but from a Biblical perspective if a person is not in fellowship with God and a citizen of His Kingdom then no amount of attendance in any so-called Christian fellowship will provide any value of eternal significance.
In fact, anyone who does not have the kingdom within then they fully qualify as a heathen as per Biblical guidelines. If you are not in Christ, fully submitted to Him in an active life of faith then you are a heathen. Simply confessing you are a child of Christ while at the same time not bearing any fruits through the natural works that demonstrate one's faith as being alive essentially means that that person's faith is dead and thus they are a heathen. James' epistle tells us this and that is confirmed by the entire council of God's word as well.
This is what God has to say about the heathen being in the sanctuaries and congregations of believers (church):
The adversary hath spread out his hand upon all her pleasant things: for she hath seen that the heathen entered into her sanctuary, whom thou didst command that they should not enter into thy congregation. Lamentations 1:10
Bottom line is, Christian fellowship is solely for the believers and for their worship of God and edification of each other.
After that we go out to make disciples of all men.