Can you clarify your phrase "silent gnosis"? On the tail of theology being a task accomplished by grace and man's works, how can this knowledge be silent? Is silence the pinnacle of theology? I read somewhere that speechless wonder is the end of philosophy; is this the same with theology?
"Silent gnosis" was maybe redundant, but I wanted to make the meaning of the term as it is used in theology a bit more clear than if I had just said "gnosis". Translating it into philosophical English is difficult, but using words like "silent", I believe, helps define its non-linguistic character. The experience of the divine light is gnosis; the encounters with our Lord in the sacraments of the Church–most supremely in the Eucharist–could also be called gnosis.
In the second letter to the Corinthians, St. Paul writes of one (traditionally taken to be himself, a fact lost on me until I read St. John Chrysostom's homilies on the letter) taken up into paradise where he hears "unspeakable words" (as the KJV puts it). The "new names" given in Revelation are another sort of direct apprehension, God's true naming of each human person.
(The joke could go that Wittgenstein was right about one thing.)
This sort of theological silence obviously does not apply only to the divine essence, which cannot be apprehended, by the examples above. Language does not give us the experience of the uncreated light; language does not give us the experience of Communion with God in the Eucharist.
As for the second question, the question really becomes one of understanding "theology" in terms that, while lacking analytic rigor, give some scope of the craft**. Pop-theological views of the differences between "positive" and "negative" theology have led to another meta-narrative, one that is furthermore not improved by an artificial synthesis of an artificial division. No experience of God is without impact on the language we have. The direct apprehension of the guidance of the Holy Spirit found in the Church guides the Church to reject false theology and recognize the true. Neither form ever exists totally without the other; the fathers demonstrate both.
Yet, if epistemic theology is not grounded in an encounter with the living God in the Church, it is a science of idols. Is that a grim picture of human cooperation with Grace in the craft of theology? I think not. It says much about the insufficiency of language before God, but little against man: Gregory of Nyssa writes that it is not blessed to know things about God, but to have Him, that we have within ourselves (for the Kingdom of God is within us) the ability to apprehend the divine things, as God made us in his image, with the likeness of his glory. We speak about God to guard the teachings of the Church (and to help lead persons to her), and that is an enormous task for human cooperation.
There are certainly tendencies to make this gnosis into a justification for a gnosticism, but language is failing me on describing where this point may be seen. I should pray, read or sleep, rather than speculate.
A few thoughts about the final question:
Where the "end" of philosophy is has to do with the question of its source and beginning. If philosophy is truly to be the love of wisdom, and not simply a will to question everything (as for Pieper, who used the latter definition to keep space between Christian philosophy and theology), then its beginning and end are found in Wisdom itself. If true philosophy can not be other than Christian philosophy, it should not surprise us: like St. Athanasius said, since when did the wisdom of the Greeks become foolish, save when the true Wisdom of God was made manifest?
*When a reply is going to be longer than a few sentences, I usually would rather write it as a new post.
**Fair play: I sometimes use the term "philosophical theology" to distinguish that part of theology which is expressed in language. It's not really a good general-use definition, but I do it, anyhow.