Many men know not what is in them, or rather what is ready for them, until they are put upon what seems utterly above their strength ; indeed, upon what is really above their strength. The duties that God, in an ordinary way, requires at our hands are not proportioned to what strength we have in ourselves, but to what help and relief is laid up for us in Christ; and we are to address ourselves to the greatest performances with a settled persuasion that we have not ability for the least. This is the law of grace ; but yet, when any duty is required that is extraordinary, that is a secret not often discovered. In the yoke of Christ it is a trial, a temptation.
from Of Temptation; volume 6 of Works, page 94
The not sending of the gospel to any people, is an act regulated by that eternal purpose of God whereby he determineth to advance the glory of his justice, by permitting some men to sin, to continue in their sin, and for sin to send them to their own place ;—as a king’s not sending a pardon to condemned malefactors is an issue of his purpose that they shall die for their faults. When you see the gospel strangely, and through wonderful varieties and unexpected providences, carried away from a people, know that the spirit which moves in those wheels is that purpose of God.
from a sermon entitled A Vision of Unchangeable, Free Mercy ; Volume 8, pages 14-15
Whatever notional knowledge men may have of divine truths, as they are doctrinally proposed in the Scripture, yet—if they know them not in their respect unto the person of Christ as the foundation of the counsels of God—if they discern not how they proceed from him, and center in him—they will bring no spiritual, saving light unto their understanding. For all spiritual life and light is in him, and from him alone.
An instance hereof we have in the Jews. They have the Scriptures of the Old Testament, wherein the substance of all divine truth is revealed and expressed; and they are diligent in the study of them; howbeit their minds are not at all illuminated nor irradiated by the truths contained in them, but they live and walk in horrible darkness. And the only reason hereof is, because they know not, because they reject, the relation of them unto Christ—without which they are deprived of all enlightening power.
from The Person of Christ, volume 1 of Works, page 81