The central and vitally essential part of God’s eternal plan was for Deity to take on flesh and live among men as a man on this earth and to ultimately die as a man for all other men. Why was it vitally essential for Deity to be “made in the likeness of men” (Phil. 2:7)? “In all things He had to be made like His brethren, that He might be a merciful and faithful High Priest in things pertaining to God” (Heb. 2:17). He is merciful, “for in that He Himself has suffered, being tempted, He is able to aid those who are tempted” (2:18). He knows what it’s like to be us!
The word used in Hebrews 4:15 is that He is able to “sympathize 
with our weaknesses.” The ASV translates the word “sympathize” as “touched with the feeling.” The word describes someone “who is affected like another by the same sufferings, impressions, emotions …one who has fellow-feeling.” It is “a fellow-feeling which derives from full acquaintance with the seriousness of the situation.” Jesus is not just our High Priest who makes constant intercession for us (7:25), but He is our merciful High Priest who cannot not be touched with the feelings of our weaknesses, because He Himself has shared in the same! What a thought!