-Reluctant at first to fight
-Used a sword -Friend of Cyrus
-Came face-to-face with Magus
-Wields the Miracle of Christ (Masamune)
-Was given the Masamune by Crono
-Is a 'disciple' of Crono
-Brother of Andrew (Cyrus is the equivalent to Andrew)
-First stayed one day with Jesus
-Was given his name by Jesus
-Was a fisherman
-Was absent from Jesus for a time, after which becoming a full-time disciple
-Was zealous and enthusiastic, but somewhat easily discouraged
-This is from some website I'm extracting facts from -- Christ, after He had spoken of the mystery of the reception of His Body and Blood (John 6:22 sqq.) and many of His disciples had left Him, asked the Twelve if they too should leave Him; Peter's answer comes immediately: "Lord to whom shall we go? thou hast the words of eternal life. And we have believed and have known, that thou art the Holy One of God"
-Peter was no stranger to Christ's miracles - He called Peter to come to Him across the lake (Matthew 14:28 sqq.); He sent him to the lake to catch the fish in whose mouth Peter found the stater to pay as tribute
-Was head of the apostles
-Christ's church was to be built upon Peter, whose name means 'rock'
-Peter given "the keys of the kingdom of heaven"
-Wished to forcefully attack the assailants at the Garden of Gethsemane
-Is first to pronounce Christ's death and ressurection
-Baptized the first non-Jewish Christians
-Used a sword -Went on extensive missions
-Martyred in Rome by crucifixion
-Like St. Peter, Frog was easily discouraged upon failing in some regard. This is most easily observed in his departure from Guardia after 'failing' to save Queen Leene, when in fact he had succeeded in saving her by aiding Crono.
-Frog and St. Peter both used swords.
-Frog's greatest ally was Cyrus; likewise, St. Peter's brother is Andrew, who is the equivalent to Cyrus.
-Frog was loosely given his name by Jesus -- it is a first meeting with him that prompts the party to call him 'Frog.'
-Frog stayed 'one day' with Crono initially; he left after Queene Leene had been rescued. Likewise, St. Peter was with Jesus for the space of a day before becoming a fully-devoted disciple.
-Similar to the above, Frog became a full apostle only after being absent from Crono's presence for a time.
-This may be a stretch, but St. Peter's fishing career may be related to Frog's status as an amphibious creature.
-Crono gave the Masamune (Trigger's equivalent to the miracles of Christ) to Frog, who subsequently wielded it and joined Crono's cause. Likewise, St. Peter was given the authority and keys to the church, and witnessed many of Christ's miracles.
-Frog's pose when casting a magic spell is reminiscent of crucifixion; St. Peter was also crucified.
-Frog has no other option but to ressurect Crono after his death; he is one of Crono's most zealous supporters. Similarly, St. Peter remarked that he had nowhere to go but by Christ - "Lord, to whom shall we go?"
-Frog can be considered head of Crono's party under the hero himself (as St. Peter was under Christ), as he is the main proponent against Magus, who the party initially believes is responsible for the destruction of the world - the quest cannot be advanced without Frog leading the way with the Masamune.
-Like St. Peter's attempt to forcefully defend Christ at the Garden of Gethsemane, Frog believes in duels and fighting.
-St. Peter's denial of Christ can be loosely related to Frog's reluctance to join Crono's party until he is presented the Masamune.
-As St. Peter continued Christ's legacy by spreading his gospel after his death, Frog returns to defend and uphold Guardia after the end of Chrono Trigger.
From: Chrono Testament