Reading the Bible is exactly the same way and fits hand in hand with this idea. Do you read the Bible one way on Sunday and then differently Monday through Saturday? Do you go along with certain ideas, nod your head, and give an amen on Sunday, only to no longer follow those same truths on Monday?
The church is full of people that fit this description and on one hand I think that is awesome because the church should be reaching people like this; but on the other hand I recognize that these people are not true disciples and if it is like the church that I grew up in than these people are probably on the role and counted in that large number of church members because we are all about the numbers often instead of life change.
So if you are a Sunday Christian then I ask you to STOP being one and just be genuine. I would rather see you be real with people, still attend church as a seeker/skeptic than to pretend to be something that you are not. In my skateboarding days we called these kids posers because they had the skateboarding style down, but were as far away from being skaters as my grandma. I am not telling you to stop attending church gatherings because you are more than welcome, but just telling you to be real because the church is a safe place for people to be real about who they are and then be surprised when they are changed by the Holy Spirit.