In earlier posts in this thread, you pointed out the key role of the Christian church in the development of individualism in the West. I was intrigued by this idea and here is what I found on the subject.
It seems that individualism is based on the idea of "individual salvation" and individual responsibility before God. From the information I found, it follows that in the pre-Christian era this idea existed, but in a rather rudimentary form: the main emphasis in Judaism was on the collective salvation of the people of Israel.
Collective identity was dominant: a Jew thinks of himself as part of Israel as the people of the Covenant. Salvation is the liberation of the people (from Egypt, Babylon, the future messianic era).
However, already in the prophetic literature (for example, in Ezekiel, Isaiah) there are notes of personal responsibility: "The soul that sins, it shall die" (Ezekiel 18:4). Here is a hint that each person is personally responsible for his actions. Thus, the idea of personal responsibility and even personal salvation was already present in Judaism, but it was not central.
Christianity has somewhat revised this approach. The focus shifts to a personal relationship with God, not to the law of Moses or belonging to Israel:
1. "I am the way, and the truth, and the life. No one comes to the Father except through Me" (John 14:6)
2. Salvation through faith, not through ritual observance of the law:
"Your faith has saved you" (Luke 7:50)
3. The principle of internal conversion - a change of mind and heart:
"The kingdom of God is within you" (Luke 17:21)
4. The promise of eternal life to everyone, regardless of nationality, gender, status and past (for example, the parable of the prodigal son, or the conversation with the thief on the cross)
Christianity makes individual salvation the central element of its message.
Christian ideas fit perfectly into the Roman paradigm. Along with the Judeo-Christian tradition, Western consciousness was powerfully influenced by antiquity.
Roman law was the first to develop the concept of persona — a legal entity, an individual as a bearer of rights and obligations.
These ideas merged with Christianity, creating a synergy: Christianity provided a metaphysical justification for the value of the individual (created in the image and likeness of God, has an immortal soul), and Greco-Roman thought provided tools for self-knowledge and social realization of this individuality (logic, law, ethics).
Further, Christian philosophy only develops and strengthens this idea, which could not but influence the social structure and the way of thinking of pre-modern contemporaries:
1. Augustine emphasizes the inner man, introspection, grace that changes personality.
2. Thomas Aquinas, and later - Protestant ethics (for example, Max Weber) - all this reveals the personal moral and spiritual autonomy of man.
3. Luther strengthens the theme of personal faith against church intermediaries.
Now you do not even have to belong to a church or go there. You do not need to belong to some people or be chosen by God. You yourself can communicate with God, and your salvation depends on your righteousness. The Protestant ethic not only strengthened personal faith, but also sanctified individual labor and accumulation as signs of divine election. Capitalism, at its core, is a system that rewards individual initiative, risk, and responsibility. The entrepreneur is the economic equivalent of the existential hero, who creates his own destiny (and his own capital).
Further, all this is transformed into individual human rights, freedom of conscience (after all, if you are not righteous, this is your problem), pluralism of opinions - it becomes a consistent development. At the same time, the idea of God as the source of everything is being debunked, as it has been replaced by faith in science.
"I don't care what John thinks, because it's his own business. I don't care how he runs the household or raises his children, because he's responsible for it himself." And the crown of all this is Kierkegaard, Heidegger, Sartre and Camus. Existentialism - as personal responsibility to oneself for one's own actions in the absence of a common meaning or common responsibility.
All this is the story of someone escaping responsibility to someone else. What I wrote above - no one is responsible for anything. The question arises: What is the next stage of liberation? Maybe now is the time to free ourselves from the need to be? After all, we are already free from everything else, including any identity, social connections, aren't we? This is exactly where I see one of those very pillars of liberalism that I spoke about earlier.
Of course, all this is too reductionist: you can't just look at Christianity as the source of everything. All the changes in public consciousness did not happen in a vacuum, but under the influence of many other things, as you noted in your comments. But this idea seemed too beautiful to me to just keep it to myself =)