Even Jesus' disciples did not always follow Him. Translate that to today. Do you know of any denomination or groups of people that claims to believe the Bible and does it all the time? I cannot think of any. Any denomination that has a democratic vote is out. God never instituted a democracy in scripture.
Any time man is involved there is potential corruption and selfishness. Even from the beginning man wanted to control the woman and the woman wanted to control the man.
So how can we have a perfect church when none exist?
What you are failing to understand is that there are no perfect Christians but there are Bibical essentials in order for a person to be recognized as a Christian.
Likewise, there are no perfect congregations but there are Biblical essentials for a congregation to be recognized as a New Testament congregation of Christ.
So your "perfect" argument is merely a straw man argument.
Roman Catholicism and many other isms do no have the Biblical essentials to be recognized as true New Testament congregations.
Biblical essentials are treated in the scriptures as absolutes without any acceptable alternatives.
For example, "if any man preach any other gospel let him be accursed" defines a Biblical essential that allows no other acceptable alternatives.
For example, "repent or perish" defines a Biblical essential that allows no other acceptable alternative.
For example, the "must" demands of scripture define absolute essentials, such as "ye MUST be born again..." etc.