“You are the Christ, the Son of the living God” was Peter’s statement about Jesus.
Jesus blessed him, said that the Father had revealed this to him, and then said that upon this rock he would build his church and the gates of hades would not prevail against it. See Matthew 16:13-20 for the full text.
How did Peter know? How did the Father reveal it? Peter knew the promises of the Messiah (the Christ) from passages of the Old Testament, and saw that Jesus fulfilled those promises. Fulfillment of God’s promises was God’s revelation to Peter and to all. In addition, Peter saw the miracles which Jesus did. These works, as Nicodemus also noted, demonstrated that Jesus was not just a man. He was sent by God (see also John 3:1-3). Jesus himself pointed to the works he did as proof of his identity (John 14:10-11). There was more! Peter was able to hear Jesus teach, and noted the uniqueness of his message and his authority (see Matthew 7:28-29). All these things were evidences given by God, which was how the Father revealed the identity of Jesus as his Son. More evidence was given to demonstrate this truth. The death, burial and resurrection of Jesus was foretold by Jesus at the time Peter made his declaration. Peter denied that it would happen, but he was rebuked for that denial. He, and his fellow apostles, eventually experienced the pain of the loss of Jesus in death and then the overwhelming joy of seeing Jesus after he was raised on the third day – just as Jesus had promised.
Yes, Jesus is the Christ, the Son of the living God. It is through him that we have our sins forgiven and renewed fellowship with God, or we can have those gifts. How is that possible? Jesus paid the price for our sins, and has revealed in the New Testament the actions we are to take to enjoy the benefits of that salvation. See 1 Peter 1:18-19 and Acts 2:22-42. The church is the spiritual ‘body’ of Jesus and is comprised of those who obey him, those who have become his disciples.
Study the Scriptures to be certain of these truths.