We are frequently reminded in the prophets that the spiritual way of life is one which is seeking God. We are to seek His face (Ps. 24:6; 27:8)- which it is impossible to behold (Ex. 33:20). Actually finding God in the ultimate sense is therefore unattainable in this life; but our whole mortal life must be lived in this spirit of seeking ultimate perfection. Seeking God is often defined in the prophets as forsaking our sins and desiring to be righteous (Amos 5:5,8,14,15). None of us are completely successful in our seeking of God, and therefore it follows that none of is completely forsakes all our sinfulness.
What unites us in fellowship is that we are all seeking the same God, the realization of the same righteousness in our lives (Zeph. 2:3). We are united by this rather than by all being righteous. It is those who seek evil with whom we find we have no fellowship; those whose direction in life is towards evil, who fail to appreciate God's righteousness. There are many with marriage problems whose turmoils have led them to value and seek true righteousness more than many of us. Again, there seems no reason to single out one particular aspect of seeking righteousness, and make this an indicator of the general direction of a believer's life. Because a couple are, e.g. separated, or because a brother occasionally drinks to excess, does not entitle us to proclaim them to be seeking evil rather than seeking God's righteousness.
There seems no reason to think that we should break fellowship with someone for not seeking God enough, if we admit that they are not seeking evil. Repentance and seeking God are related; thus Israel's restoration came when they were seeking God and (i.e.) repented (Jer. 29:12-14). However, there is good reason to think that Israel at this time were still spiritually weak; some of them had a desire to seek righteousness, and God accepted this. The connection between repentance and seeking God means that to withdraw fellowship from someone for not repenting enough, is to disfellowship them for not seeking God enough. The implication is that the rest of us have sought God enough- and therefore found Him. This is pure self-righteousness. In conclusion, God wants us to be seeking Him, but this seeking God does not imply complete repentance and forsaking of sin.