I'm not exactly sure what you're trying to ask, xls.
Our Lord established one Church. He said He would build His Church not churches. Historically it can be demonstrated that the only Church that fits this description is the Orthodox Church. These other "christian" communities may contain Christians who in some way that we do not understand are members of the true Church: the One, Holy, Catholic and Apostolic Church.
I tend to agree with Paradosis, although I'd like him to expand upon his post. St Paul said in Romans:
7:19 For I do not do the good I want, but I do the evil I do not want.
7:20 Now if (I) do what I do not want, it is no longer I who do it, but sin that dwells in me.
7:21 So, then, I discover the principle that when I want to do right, evil is at hand.
7:22 For I take delight in the law of God, in my inner self,
7:23 but I see in my members another principle at war with the law of my mind, taking me captive to the law of sin that dwells in my members.*
7:24 Miserable one that I am! Who will deliver me from this mortal body?
7:25 Thanks be to God through Jesus Christ our Lord.
We are all going to fall into sin from time to time. The key, as far as I can see, is that sin does not have dominion over us. When that happens (i.e. we are slaves to porn let us say since that is the example being used) then one has to wonder about the depth of one's commitment to the Lord and the distinct possibility that the Holy Spirit may not indwell such a person.