“Is the above biblical?”
Not that I am aware of. +Nilus of Sinai, though a noted theologian and biblical scholar of his time, also wrote from his own ascetical experience. Does something need to be “biblical” to be of value to our theosis, bb? Surely you haven’t fallen that far from the Magisterium, have you?
+Nilus was canonized by The Church; the one which established the canon of the NT. He is considered an Eastern Father. That is sufficient for any Catholic absent a demonstration that a teaching of a Father is outside the consensus patrum. Are you aware of anything written by +Nilus which is outside the consensus patrum, bb? You may not like what he said; there is no question but that he would soundly and loudly reject any notion of a sort of Universalism in Christianity; in fact, just as both the Latin Church and Orthodoxy declare such notions heretical today.
The Bible is one of two essential works, IMHO, the other being the Catechism of the Roman Catholic Church, brought out in a magisterial new addition in the early '90s by Joseph Cardinal Ratzinger, who is now Pope Benedict XVI. As Prefect of the Congregation for the Doctrine of the Faith, Cardinal Ratzinger presided over the Magisterium, which is of course biblically based.
My confession of the Faith is summed up in the Nicene Creed. What exactly are we arguing about here, Kolokotronis?