Here is what Ravenhill meant:
Romans 9:6-8 (Not all of Israel is Israel)
6Not as though the word of God hath taken none effect. For they are not all Israel, which are of Israel:
7Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called.
8That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.
This statement by Ravenhill is like saying not all Christian churches are actually the body of Christ. God knows who is the real body of Christ.
Church is referred to as many things in the bible:
The Bride, the word makes many mentions of this throughout...not just in Revelation.
As a virgin
As a wife
As children
As lambs
As sheep....and so on.
Ravenhill is simply stating a truth. Yet, we must be carefull that we do not take this statement and apply it to individuals. This decision of who really is a Christian is only answered by God...we should not look into our own congregation and start deciding along with God...this person will not be part of the bride (the church) when Christ comes back.
Our job is to encourage and correct those that are in the "system" as my brother so well put it, and help them to become a part of the virgin bride.
James 4:11-17
11Speak not evil one of another, brethren. He that speaketh evil of his brother, and judgeth his brother, speaketh evil of the law, and judgeth the law: but if thou judge the law, thou art not a doer of the law, but a judge.
12There is one lawgiver, who is able to save and to destroy: who art thou that judgest another?
13Go to now, ye that say, To day or to morrow we will go into such a city, and continue there a year, and buy and sell, and get gain:
14Whereas ye know not what shall be on the morrow. For what is your life? It is even a vapour, that appeareth for a little time, and then vanisheth away.
15For that ye ought to say, If the Lord will, we shall live, and do this, or that.
16But now ye rejoice in your boastings: all such rejoicing is evil.
17Therefore to him that knoweth to do good, and doeth it not, to him it is sin.