Acts 2:34-36, 1 Pt 1:10-11
The Old Testament prophesied that Christ would suffer, die, and be resurrected. (1 Pt 1:10-11)
1 Pt 1:10 Of which salvation the prophets have enquired and searched diligently, who prophesied of the grace that should come unto you: 11 Searching what, or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow.
Jesus revealed himself to his disciples by telling them that Christ would suffer, die, and be resurrected. In other words, Jesus showed Himself to be the Christ. (Lk 24:26,46)
Lk 24:26 Ought not Christ to have suffered these things, and to enter into his glory? 46 And said unto them, Thus it is written, and thus it behooved Christ to suffer, and to rise from the dead the third day:
During His public ministry, Jesus showed his disciples that he was the Christ. But the disciples did not believe it. But after Jesus was resurrected, it was believed that Jesus was the Christ. (Jn 2:22)
Jn 2:22 When therefore he was risen from the dead, his disciples remembered that he had said this unto them; and they believed the scripture, and the word which Jesus had said.
Peter testified that Jesus was resurrected as a sure proof that Jesus was the Christ. (Acts 2:34-36)
Acts 2:34 For David is not ascended into the heavens: but he saith himself, The Lord said unto my Lord, Sit thou on my right hand, 35 Until I make thy foes thy footstool. 36 Therefore let all the house of Israel know assuredly, that God hath made the same Jesus, whom ye have crucified, both Lord and Christ.