Gnosticism is probably the most abused word in the modern world. Nearly all of its uses in modernity rip it out of its historical meaning and context to use it as some sort of theological bludgeon, and this is no exception. Gnosis is NOT faith, it is not any kind of faith, gnosis refers to a secret esoteric knowledge which enables the pneumatic who discovers it to escape the material wold and return his divine spark to the pleroma. There is absolutely nothing in common between the Gnostics and the Christian faith.
Imagine if there was a transcendent world beyond this one, of which this one is merely a shallow copy, a perfect world which was distorted into this one by a creature-god called a demiurge. If you're familiar with church history you should know this is a description of the Gnostic heresy, but if you're familiar with the history of philosophy, you should also recognize it as a description of Platonism. That's because Gnosticism is a thoroughly pagan Greek philosophical construct which is descended from Plato's philosophy rather than the true religion, which merely stole a few terms and concepts from the latter. The founders of Gnosticism were probably those on Mars hill who scoffed at the resurrection. The Gnostic pleroma is based off Plato's realm of forms, and not anything in scripture.
OP, you are a heretic. We believe in everything the Old Testament says because it is the word of the true and living God, the creator of all things in heaven and on earth and under the earth. Yahweh is God, and if you don't believe that, you are still in your sins and the truth is not in you. If there's no wrath of God in the cross, there's no mercy of God in it either. Repent and believe the gospel.