The idea of God raising the dead was generally accepted throughout Judaism as belonging only to Him.  One Rabbinic saying was, “Three keys are in the hand of God and they are not given into the hand of any agent, namely that of rain, that of the womb, and that of raising the dead.” (qt’d in Morris p. 314)  And yet Jesus states that He will raise from the dead whomever He chooses.  He is speaking of a spiritual resurrection but He will also exercise physical raisings later in His ministry: the son of the widow of Nain, Jairus’ daughter, and Lazarus. This is also one of the “greater things” that Jesus was referring to in the previous verse. Giving life to that which was dead is greater than healing infirm limbs.

Note that Jesus said “whom he will.”  The Son gives life to whomever He chooses, like He did with the healing of the man at the pool. Why did Jesus choose that particular man among so many sick? I don’t know, but it was His choice and this is another attribute of God — sovereignty (#Psa 97:1, 103:19). God is God and so is the Son. He will give eternal life to the person He and He alone chooses.

Ps 97:1  The LORD reigns, let the earth be glad; let the distant shores rejoice.

Ps 103:19  The LORD has established his throne in heaven, and his kingdom rules over all.

Note that we can not command the miracle of rebirth ourselves, even by doing all the things the Bible tells us to do to receive eternal life. We must be chosen. We are totally dependent upon God for our salvation (#Joh 6:44).

Joh 6:44  “No-one can come to me unless the Father who sent me draws him, and I will raise him up at the last day.