Peter was originally named Simon, but Jesus later renamed him Cephas (Peter).
If we examine the other Gospel books apart from the Book of Matthew, we find that the renaming of Peter occurred not when Peter confessed Christ in Matthew 16:17 but when they first met in John 1. The renaming of Peter after declaring Jesus as Christ is unique to the Book of Matthew.

Most Christians have always thought “Peter means “rock,” and some even go further to say that Peter was the “rock” on which Jesus’ ministry was built.
However, in the Greek language, we discover that the words translated as “Peter” and “rock” are not the same.
In Matthew 16:18 (KJV), Jesus says, “And I say also unto thee, That thou art Peter (πέτρος), and upon this Rock (πέτρᾳ) I will build my church; and the gates of hell shall not prevail against it.”
“Peter” (πέτρος) — Petros means “stone,” while “rock” (πέτρᾳ) — Petra, refers to a hill or cliff.
According to Abbot-Smith, Petros (masculine noun) properly means “a stone (pebble), such as a small rock found along a pathway.”
Petros is a transliteration of the Greek word meaning “small stone” or “piece of rock,” while Petra refers to a larger mass of rock, such as a cliff or boulder.
Additionally, Jesus spoke Aramaic, where “Kepha” from “Kefa’” means “stone” (referring to a pebble or a smaller piece of stone), not a rock or boulder. However, in most New Testament translations, “Peter,” which means “stone,” has been rendered as “rock.”

So, why was Simon nicknamed Kefa (Petros, Stone)?
Our cue comes from the Parable of the Sower,
Matthew 13:5–6: “Some fell upon stony places, where they had not much earth: and forthwith they sprung up, because they had no deepness of earth: And when the sun was up, they were scorched; and because they had no root, they withered away.”
Jesus explains this parable later in Matthew 13:20–21:
“But he who received the seed on stony places, this is he who hears the word and immediately receives it with joy; yet he has no root in himself, but endures only for a while. For when tribulation or persecution arises because of the word, immediately he stumbles.”

Simon, Kefa, demonstrates this behavioral pattern “When trouble or persecution comes because of the word, they quickly fall away” several times.
I will mention two instances:
The first was when Jesus was walking on water, and Peter asked to join Jesus. Peter started well, but when he was disturbed by the wind, he doubted and started sinking, and Jesus called him a man of little faith (Matthew 14:28–31).
28 “Lord, if it’s you,” Peter replied, “tell me to come to you on the water.”
29 “Come,” he said. Then Peter got down out of the boat, walked on the water and came toward Jesus.
30 But when he saw the wind, he was afraid and, beginning to sink, cried out, “Lord, save me!” 31Immediately Jesus reached out his hand and caught him. “You of little faith,” he said, “why did you doubt?”

The second instance is the famous denial of Jesus, which Jesus had already predicted. After Jesus was arrested, despite Peter’s initial bravado, when he got to the courtyard, Peter not only denied Jesus three times but also invoked a curse on himself just to prove his denial of Jesus (Mark 14:69–71).
71 He began to call down curses, and he swore to them, “I don’t know this man you’re talking about.”


The Roman Catholic Church has for years looked to Matthew 16:18 in an attempt to justify having a pope as the head of its church. But tracing the name of Peter with Jesus’ parable and Peter’s attitude, did Jesus really set his ministry foundation on an unstable person like Peter?

Who is meant by “this Rock” in Matthew 16:18–19?
After Peter declared his confession of faith in the Lord Jesus, the Lord said to him: “You are Peter (Petros), and on this rock (Petra), I will build My church… I will give you the keys of the kingdom of heaven. What you bind on earth will be bound in heaven, and what you loose on earth will be loosed in heaven” (Matthew 16:18–19).”

Petra in the original Greek means "rock" and might refers to the revelation that Jesus as the Christ, the Son of the living God.
Matthew 16:16
Simon Peter answered, “You are the Messiah, the Son of the living God.”