God has revealed these to us by the Spirit. For the Spirit searches all things, even the deep things of God.
[1 Cor 2:10 NET]
The Spirit of God who dwells in a man, making his body his temple, searches the deep things of God; for there is in these deep things a most heavenly treasure, which is to be searched into, that it may be found. What depths do we sometimes see in a single text of Scripture as opened to the understanding, or applied to the heart; what a depth in the blood of Christ—how it “cleanses from all sin,” and if from all sin, it must cleanse away millions of millions of the foulest sins of the foulest sinners. What a depth in his bleeding, dying love that could stoop so low to lift us so high! What a depth in his pity and compassion to extend itself to such guilty, vile transgressors as we are! What depth in the eternal counsels and unspeakable wisdom of God to contrive such a plan as was accomplished and brought to light in the incarnation and death of his dear Son, that thus mercy and justice might meet together without jar or discord, every attribute of God be fully honored, and yet that those who deserved hell should be lifted up into the enjoyment of heaven.
What depths, also, there are in our own heart, not merely of sin but of grace, for true religion has its depths which the Spirit searches and brings to view. Thus if we have any faith, it lies very deep, for it is hidden in the heart, and sometimes so hidden as to be almost, if not altogether, out of sight. The Spirit then searches for it, and brings it out and up. So if we have any love, it strikes its root into the inmost recesses of our affections, and therefore needs to be searched into; or any hope, it lies like the anchor at the bottom of the sea. It therefore has to be searched into that it may be made manifest that it is sure and steadfast and enters within the veil.