United with Christ

For if we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his. (Romans 6:5)

The theme here is agricultural. We have been united, planted together, grown together, in the various translations. Jesus is the root and trunk. We, the branches, are united in Him.

I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing. (John 15:5)

In the Romans verse where it speaks of united with Christ, it means 'to grow together'. Though Christ is the first and the last, and we were grafted in, we are now growing together. I find this mind-staggering.

S. Lewis Johnson preached on this section of Romans, and he said in this sermon,
So he says that we should not “henceforth serve sin.” Benjamin Breckinridge Warfield who was one of the greatest of the theologians of the 20th Century has said with reference to Romans 6 in one of his writings, “He cures our sinning precisely by curing our sinful nature. He makes the tree good that the fruit may be good. He eradicates our sinfulness.”
Romans 6:7 KJV: For he that is dead is freed from sin.  In Charles Spurgeon's verse expositions of the bible, Spurgeon explained:
The man is dead. The law cannot ask more of a criminal than to yield his life. If, therefore, he should live again after death, he would not be one who could suffer for his past offences. They were committed in another life, and “he that is dead is freed from sin.”
 Jesus Christ is the most magnificent person in the Universe.