In his essay Existentialism and Human Emotions, Sartre asserted that "In choosing myself, I choose man." This implies that there are no purely personal choices:
When we say that man chooses his own self, we mean that every one of us does likewise; but we also mean by that that in making this choice he also chooses all men. In fact, in creating the man that we want to be, there is not a single one of our acts which does not at the same time create an image of man as we think he ought to be. To choose to be this or that is to affirm at the same time the value of what we choose, because we can never choose evil. We always choose the good, and nothing can be good for us without being good for all.
I was reminded of Sartre's claim while reading an essay by Bernard Lewis in this month's issue of The Atlantic. Lewis contrasts two approaches to religious matters: triumphalism (the worldview to which I subscribe is right, and all the others are wrong) vs. relativism (there are many paths to God or heaven or happiness). Judaism is an example of a relativist religion, since it holds that one can be "saved" in faiths other than Judaism (with the caveat that such faiths must be monotheistic). Old-time Christianity was triumphalist (everyone but good Christians would go to hell), and the main stream of Islamic thought is triumphalist to this day (although both Islam and Christianity have, like Judaism, traditionally tolerated other monotheistic religions to some extent).
For a long time I too was a triumphalist, although in the realm of philosophy rather than religion (I ceased believing in a god at the age of nine). Turning monotheistic toleration on its head, I thought that only atheists were on the right path. Even further, I held that only adherents of the philosophy I had come to accept (Ayn Rand's philosophy of "Objectivism") were correct, and that everyone else was wrong. Randian triumphalism is the rule in Objectivist circles, and among orthodox followers of Rand the harshest criticisms are reserved for those who dare to express toleration for alternative viewpoints. Yet moving beyond triumphalism involves more than merely "tolerating" others' ideas -- it means actively respecting them as sincere attempts at coming to understand reality and human experience. Unfortunately, not every viewpoint results from a sincere attempt at understanding; but I've found it valuable to try to see others' viewpoints in that way, at least until proven otherwise.
Not that I'm a complete relativist. After all, there is this little thing called evidence...