What does Sartre mean by “Existence precedes essence?” What is essence and existence? What makes him conclude this? What further effect does this have on meaning, value, and freedom?

Essence in this case refers to the ancient philosophical idea (most closely associated with Plato) that all things have a predefined, ideal set of characteristics. For instance, the Essence of a chair is that it has four legs, a back, and people sit on it.

However, not everything matches its Essence. You might have a chair with three legs, or a broken back, or that no one sits on. The actual details of a particular chair make up its Existence.

The idea that Existence precedes Essence is that –for human beings –there is no predefined pattern that we must fit into. We live our lives, and that in turn defines what we truly are, not any idealized set of characteristics. This idea is the heart of Sartre’s version of Existentialism.

The implications are that we must create our own meaning, place our own value on our acts, and that our individual freedom is absolute and unbounded.

As a side note, Sartre, although an atheist, gave what I consider to be one of the best ever descriptions of God, as the “Union of Existence and Essence”, meaning that God is the full Existential realization of every perfect, ideal or Essential attribute of God. Sartre, of course, described that as an impossibility, but it is also a good description of what a believer believes God to be.

Would you agree with those such as Alister McGrath that Christianity is rationally defensible, or would you say that the rational aspect is unimportant? If the latter, how would you respond to charges of thoughtless fanaticism in your religiosity?

This is a fantastic question.

I begin my answer by noting that rationality is overvalued and its capacity overestimated. The ability of the human mind to apprehend what it considers is vast, but not unlimited. Not everything, therefore, can be understood in ways that make apparent sense and align with all the other things that we know. In particular, God would not be God if He could be fully comprehended. For this reason, I side with those who call faith unreasonable.

As a student of Kierkegaard, however, I also note that the central paradox of Christianity, of God present with us, is no more of a paradox than the paradox of existence itself. Why should there be something rather than nothing? Why does our existence mainifest in the shape that it has, rather than in some other form? Why does each of us individually and idiosyncratically exist, and why are we bound by space and time? These are questions that have no rational answers, yet we live with the paradoxes they imply because we lack the ability to do otherwise.

This leads me to what I take to be the key Kierkegaardian insight: The mystery of Christ is not only on a par with the mystery of existence, it is in fact the same mystery. The mystery of why God would enter the universe and suffer and die is the very same mystery as why that universe would exist at all, and why there would be suffering and death within it in the first place.

All this having been said, however, I think there’s a danger in dismissing faith as merely or dogmatically irrational. The believer, I would claim, is not simply a believer in defiance of all evidence –which would indeed make him the thoughtless fanatic of your query.  Speaking as a believer, I would say that God has demonstrated His existence to me with evidence that is plentiful and personally compelling –yet not of a sort that lends itself to conclusive depersonalized proofs.

My aim in making such a claim is not to present a case for God’s existence capable of convincing the non-believer, but to advance the argument that the intrinsic irrationality (or what we might call the “transrationality”) of faith does not necessarily imply that the person who embraces faith must do so in an irrational manner. One may safely assume that the person who believes does so for personally valid reasons, even if those reasons are not easily understood by the non-believer.

This, it seems to me, is the best way to approach the ontological proofs of theological rationalists like Aquinas and Descartes, the apologetics of someone like C.S.Lewis, or the calculated wagers of Pascal and his ilk –not as attempts to equate faith with reason, but rather as ways of demonstrating that faith and reason are at least compatible with one another; and therefore that the embrace of one does not necessitate the destruction of the other.

Is Lucifer interpreted as pining for the God he once loved and has been cast down by” sorry more of a theological question here (agnostic’s novel research)

Thanks for your question. One important thing to remember here is that with a few brief exceptions, the devil is barely mentioned in the Bible itself –and in fact, the one mention of “Lucifer” by name may not even refer to the devil at all. So from that point of view, there isn’t really an “official” answer to your question. The majority of the lore about Lucifer in the Western tradition comes from Dante’s Inferno and Milton’s Paradise Lost, so if you want to be in tune with the general opinion, those would be the sources to check. Generally the understanding is that Lucifer was the best and brightest of the angels, until he tried to arrogate God’s place as ruler of the universe.

None of this answers your question, but given Lucifer’s extra-canonical nature, I think you’d be perfectly justified in exploring your own interpretation. You might also find it interesting to note that in the Islamic tradition, the devil is considered a “loyal” but misguided servant of God, whose chief crime is his jealousy and hostility towards mankind, and whose destiny is to be reconciled to God at the end of time.