Shared ground
Hebrews 2:17–18 presents Jesus’ full sharing in human life as necessary, not optional: he “had to” be made like his “brothers in all things.” The stated purpose is that he might become a certain kind of high priest—both merciful toward people and faithful in representing them “in things pertaining to God.”
The passage also ties that priestly role to dealing with human sin: he “makes atonement for the sins of the people.” And it links his present ability to help with his past experience: because he suffered in connection with being tempted (tested), he is able to help those who are tempted.
Where interpretation differs
One difference is what “in all things” is meant to cover. Some read it as stressing total, real humanity (every essential feature of human life). Others read it as “fully like them in the relevant ways for his mission,” without claiming the verse is answering every question about the limits of that likeness.
Another difference is who “his brothers” and “the people” refer to in scope. Some take the wording as mainly about the believing community he represents. Others take it more broadly as humanity, with a later narrowing in Hebrews to those who benefit from his priestly work.
A further difference is how “tempted” should be heard. Some hear it mainly as inner enticement toward wrongdoing. Others hear it more as “tested through suffering,” including pressures like fear, shame, and persecution.
Why the disagreement exists
The key phrases are broad and can be used in more than one sense. “In all things” can be read as comprehensive likeness, but the text does not list each category. “Brothers” can function as a family term for a community, but it can also echo the larger argument of the Son sharing “flesh and blood” in the surrounding context (2:14–16). And the word translated “tempted/tested” can describe both moral enticement and hardship that reveals fidelity.
What this passage clearly contributes
Explicitly, the text claims Jesus’ shared humanity is the basis for his priestly qualification: he can represent people before God as merciful and faithful. It also explicitly connects his help for the tempted to his own suffered testing.
By theological inference (going beyond what is directly stated), many readers conclude that Jesus’ help is not merely sympathy but active support grounded in experience, and that his priestly work addresses both the reality of sin (“atonement”) and the reality of human weakness under pressure. The passage does not spell out how that help is experienced, but it grounds the claim in what he has endured and in what he now is as high priest.