At the end of Hebrews 4 and the beginning of Hebrews 5, we see that it’s critically important for healthy Christian living to recognize Christ as a merciful high priest who can sympathize with our weakness. He has been made like us. This is the argument in the second half of Hebrews 2 as well. It is absolutely right that Jesus sympathizes with us in our weakness. However, while He becomes like us in our humanity, it doesn’t mean that He has to take on a sinful nature.
To talk about a sinful nature is to talk about our internal desire for sin. I have a sinful nature because there is a desire in me to do sinful things, but a temptation I face is different from the desire I have to do something.
Jesus had no sinful desires. There was no longing to murder or lie or to glorify Himself as to receive glory from men. Now, that doesn’t mean He can’t sympathize with us, because we see that He was tempted just as we are. He was tempted with power and with food. He was tempted to commit suicide. These were interesting temptations to be faced with. He was also faced with suffering. He was hungry. He saw the death of a friend. He experienced the most excruciating physical pain on the cross.
Because Jesus is truly human, He can sympathize with us as we are tempted, as we suffer, as we are bereaved, and as we struggle. He can sympathize with us in our weaknesses, but that doesn’t mean that we can wonder, “Will there be a desire in Him to do something evil now?” He can sympathize, but He sympathizes with us with a loving purity, never tainted by any viciousness, cruelty, abusiveness, or sin.