15 For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin.
Since we have a High Priest, believers should hold on to their convictions (He 4:14). He will care for His own. Although He is in heaven, He still can identify with those who belief in Him.
we do not have a High Priest who cannot sympathize [feel with] with our weaknesses,
Jesus stepped foot on earth and identified with human beings by becoming a human being. Since He did what He did, He can sympathize with Christian struggles and “weaknesses.” He is capable of sympathizing with everything we face.
The double negatives “not” and “cannot” strongly affirm that we do have a High Priest who can identify with our weaknesses. This is the positive side of the contrast.
but [rather] was in all points tempted as we are,
The Devil tempted Jesus to sin (Mt 4:3,6). “Tempted” includes both temptation to sin and to endure trial. Temptation is not sin. Yield to temptation is sin. Jesus did not yield to temptation as we see in the next phrase. Jesus confronted anything that we might experience in principle.
yet without [apart from] sin.
Jesus was sinlessly perfect. He did not need to pay for any sin He committed. He was sinless (He 7:27; 9:14; 2 Co 5:21; 1 Jn 3:5). Yet He was tempted by the devil (Mt 4:1f).
Jesus was weak in that He shared the limitations of being a human which included liability to sin. He did not sin but was tempted by the devil to sin. He lived “without” or completely apart from sin. Jesus was tempted to sin in His humanity, not His deity. He did not use His attributes as God to resist sin. However, as God He understood the nature of sin like no human could possibly grasp.
Jesus empathizes with us like no other.
The Son of God stepped foot into a human body so that He might be an empathetic High Priest on our behalf. Our Lord fully understands what we are going through. His experience was not far removed from our experience. He did not share our exact experience, but He experienced that which leads to sin (He 10:34).
There is a debate in theology as to whether Jesus could have sinned. If He could not sin, then how could His temptation a true human experience. Note that this verse only says that He did not sin, not that He could not. Also, temptation to sin is not the same as to commit a sin.