"No, the crucial point of Christianity is the political one, which is that it associates God with the lowest of the low, while it promotes the countercultural message that secular or ungodly human progress is futile."
“Paul, you are mad; your great learning is turning you mad.” -- Agrippa to Paul, Acts of the Apostles 26:24b
The crucial point of Christianity is the death, burial and resurrection of the only-begotten Son of God, and its consequence: the redemption of mankind. More fundamentally, it is about having a dynamic relationship with God.
People for whom politics (aka power) is the crucible in which all things are tried seem unable to appreciate a different perspective. Your description trivializes faith by reducing it to moralism.
Christian emphasis on caring for the poor isn't political; it's about love. When Jesus was asked which of the Commandments was the most important, he spoke of love: loving God and loving neighbor as oneself. "On these two commandments depend all the law and the prophets." The point isn't to glorify poverty but be especially careful to love those who are most in need of it.
"Jesus’s act of self-sacrifice was divine, for Christians, in that it demonstrated flawless alienation from natural and political norms."
The Christian view is that Jesus' act of self-sacrifice was divine because He is divine, and it is salvific because he was the perfect sacrifice, the unblemished Lamb of God who takes away the sins of the world.
"That’s Christianity’s existential problem in the modern period. The problem is that the existence of this religion makes for a performative self-contradiction. An organized religion that’s founded on the promotion of the victim’s resentment towards earthly success is doomed from the start."
This is so far off the mark that I honestly don't know how to begin. You mistake appearances for substance. You see nothing but the manifestation of faith within a cultural context, or series of cultural contexts, and decide that it is nothing more than its appearances.
THIS is the central problem with your thesis and your perspective: mistaking accidents for substance, and failure to appreciate metaphysicality as real or significant -- when it is the metaphysical that gives meaning to the physical in the first place!
This is much too fundamental an error to attempt to correct in this venue, nor would it be efficient for me to try. But the basic problem, as I said, is dismissal or failure to appreciate the spiritual and its relationship to the physical. These are not opposed in essence; indeed, they cannot be, for it is the spiritual that gives the physical meaning.
