"... the son can do nothing by himself ..." (John 5:19)

"I tell you the truth, the son can do nothing by himself; he can do only what he sees his father doing, because whatever the father does the son also does.” (John 5:19)
Here Jesus is using a metaphor to describe the relationship that exists between himself and the Supreme Being.

Many have misinterpreted this as the "son" being Jesus and the "father" being God. This is essentially the message, yes. But Jesus is using an analogy so that people can understand the intimate type of relationship that exists between God and His dedicated follower.

Does God have only one son?

Many sectarian interpreters have indeed considered Jesus to be the only "son" of God. But this is simply not true. The Bible contradicts the notion that Jesus is the only "son" of God:
When human beings began to increase in number on the earth and daughters were born to them the sons of God saw that the daughters of humans were beautiful, and they married any of them they chose. (Genesis 6:2)
The Nephilim were on the earth in those days—and also afterward—when the sons of God went to the daughters of humans and had children by them. They were the heroes of old, men of renown. (Genesis 6:4)
Now there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them. (Job 1:6)
Again there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them to present himself before the LORD. (Job 2:1)
When the morning stars sang together, and all the sons of God shouted for joy? (Job 38:7)
"Blessed are the peacemakers, for they shall be called sons of God." (Matt. 6:9)
But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name (John 1:12)
For as many as are led by the Spirit of God, they are the sons of God. (Romans 8:14)
For the earnest expectation of the creation eagerly waits for the revealing of the sons of God. (Romans 8:19)
You are all sons of God through faith in Christ Jesus. (Galatians 3:26)
Furthermore, does it even make sense that God could only have one son? Most human males can have multiple sons. And God can only have one? Such a notion that God only has one son is preposterous.

The fact is, the Supreme Being has created so many children that it boggles the mind. He is unlimited in His potency to create, and "begot" children.

However, Jesus' use of "son" applies further to creation. He is speaking of a relationship where one becomes a worshiper of God. A devotee of God. A lover of God.

Jesus' metaphor discusses dependency

Jesus' metaphor, which followed, "I tell you the truth," was told to his followers because each of them had the opportunity to regain their relationship with God and become dedicated to God. This would affect the type of relationship that Jesus is speaking of:

Taking shelter of God. Becoming dependent upon God.

Such is the opportunity for each of us. Any of us can choose to take shelter in God and become one of God's dependents. One of God's lovers. This is what Jesus is trying to teach his students.

Jesus was also illustrating that indeed, he is to be included as someone who has taken shelter in God. Jesus was responding to those wanting to criticize Jesus, saying that Jesus was putting himself equal to God (John 5:17). Jesus clarified that because he (and any of God's loving servants) is dedicated and dependent upon God, the actions of God's loving servants simply reflect God's will.

This occurs in any loving relationship. A person who loves another will do the will of and act on behalf of the one they love. This is the essence of Jesus' life, and the essence of Jesus' relationship with God.