The core of the meaning appears to rest in the two words

 for a "rock." If Matthew recorded that Christ used the same

word both for (1) the proper name of Peter and (2) the

foundation on which Christ says he will build the church,

then an interpretation follows that the foundation of the

church is Peter.

Because the Word of God as recorded in Matthew had to be

intelligible in its literalness for all people including the more

simple people of the early centuries of the Church, a more

involved interpretation demanding extensive hermeneutics

and linguistic acumen would be unwarranted. Ultimately, when

there are differing interpretations, the principle question then

becomes, "by what authority is the truth appealed."