Because Jesus said so. Have faith in the word of God!
Peter himself told us that the rock, *petra* was Christ.
JESUS is the chief cornerstone.
No He didn't. Jesus is the Rock and the ekklesia is built on the belief in that Rock. God Himself said there was no other rock.
Isaiah 44:8 Do not tremble, do not be afraid. Did I not proclaim this and foretell it long ago? You are my witnesses. Is there any God besides me? No, there is no other Rock; I know not one."
Jesus is the rock. No man is that. His church is built on Him and I am not talking about the Catholic one. He knew no man is perfect. Do not let a man take the place of Him. Like I have said on here before, “Jesus is the answer, the only answer.”. He is the only forgiver of sin. Some on here depend on man and a church way too much. I had a very hard day yesterday because it was the 11th anniversary of my daughter’s death. When I turned my pain and sadness over to Him, I felt much better. I know He is the answer.
Catholics want Peter/Cephas to be the first Pope and “The Church Leader”, but your Bible doesn’t teach that in any capacity. Your Bible actually teaches that James made the decisions for the early Church. Verse 19, JAMES reached the decision not anyone else! God shows no partiality. Something else to think about, the names listed in verse 9 James is first and John is last putting Cephas in the middle. If Cephas was the leader wouldn’t his name be listed first? God wants us to put him as our King/Leader as noted by OT Scripture.
1 Samuel 8:6-7New Revised Standard Version Catholic Edition (NRSVCE)
6 But the thing displeased Samuel when they said, “Give us a king to govern us.” Samuel prayed to the LORD, 7 and the LORD said to Samuel, “Listen to the voice of the people in all that they say to you; for they have not rejected you, but they have rejected me from being king over them.
Acts 15:13-19New Revised Standard Version Catholic Edition (NRSVCE)
13 After they finished speaking, James replied, “My brothers,[a] listen to me. 14 Simeon has related how God first looked favorably on the Gentiles, to take from among them a people for his name. 15 This agrees with the words of the prophets, as it is written,
16 ‘After this I will return,
and I will rebuild the dwelling of David, which has fallen;
from its ruins I will rebuild it,
and I will set it up,
17 so that all other peoples may seek the Lord—
even all the Gentiles over whom my name has been called.
Thus says the Lord, who has been making these things 18 known from long ago.
19 Therefore I have reached the decision that we should not trouble those Gentiles who are turning to God,
Galatians 2:6-10New Revised Standard Version Catholic Edition (NRSVCE)
6 And from those who were supposed to be acknowledged leaders (what they actually were makes no difference to me; God shows no partiality)—those leaders contributed nothing to me. 7 On the contrary, when they saw that I had been entrusted with the gospel for the uncircumcised, just as Peter had been entrusted with the gospel for the circumcised 8 (for he who worked through Peter making him an apostle to the circumcised also worked through me in sending me to the Gentiles), 9 and when James and Cephas and John, who were acknowledged pillars, recognized the grace that had been given to me, they gave to Barnabas and me the right hand of fellowship, agreeing that we should go to the Gentiles and they to the circumcised. 10 They asked only one thing, that we remember the poor, which was actually what I was eager to do.