Answer Request:
Is Christ's Church built on Peter or all living stones of truth? Did God reveal the truth to Peter that Jesus is The Rock?
The Greek word translated "church" in the New Testament is ekklesia. A literal translation of ekklesia would be "a called-out assembly". Thus, when God calls one out, to separate them, it is for a purpose. In other words, there is a specific function that this entity should fulfil. For example, God separated the nation of Israel for a purpose. Israel can be identified as an ekklesia, (or church in modern English).
Deut.7:6 For thou art an holy people unto the Lord thy God: the Lord thy God hath chosen thee to be a special people unto himself, above all people that are upon the face of the earth.
Num.23:9 For from the top of the rocks I see him, and from the hills I behold him: lo, the people [Israel] shall dwell alone, and shall not be reckoned among the nations.