purpose of John's writings

John 20 records the events following Christ's Resurrection. I was impressed that vs. 8-9 reveal that the disciples didn't realize Jesus would be raised to life, even though Christ told them this several times. Also, I appreciate Thomas's confession that Jesus is both Lord and God. But, perhaps the most poignant statement is John's comment in vs. 30-31:

30 The disciples saw Jesus do many other miraculous signs in addition to the
ones recorded in this book. 31 But these are written so that you may continue to
believe that Jesus is the Messiah, the Son of God, and that by believing in him
you will have life by the power of his name.

I think this is a concise purpose statement that could be extended in general to the whole Bible.

Prayer
Lord Jesus, I believe that You are the Son of God, the Messiah Who redeemed mankind from the penalty of eternal death to a righteous relationship with the Father, Son, and Spirit. I put my Faith wholly in You, for you are the Rock of my Salvation. Amen.