John Gill's Exposition of the Whole Bible
Psalms 18:30
[As for] God, his way [is] perfect,.... Or "without spot" m, as the Septuagint render the word; without any just charge of inequality, or unrighteousness; such is God's way of providence, though sometimes his methods of providence are cavilled at by wicked men, and murmured at by his own people: they are at a loss, at times, to reconcile promises and providences together, and to account for the justice and equity of them; these ways of his are unsearchable, and not to be traced out by them; but when his judgments will be made manifest, the wisdom, goodness, and righteousness of them will be clearly discerned, and they will be admired; for they are all of a piece, and perfectly consistent with the attributes of God: and such also is his way of grace, and method of salvation; it is agreeable to all his perfections, and according to his purposes, counsel, and covenant; this being resolved on in his breast, contrived by his wisdom, and concluded on in the covenant, has been effected and finished by his son; and his inward way of working upon the heart, though at present imperfect, will be completed; he is a rock, and his work is perfect, and all his ways are judgment: whatever way or method he contrives and enters upon, whether in providence or grace, he pursues and brings to an issue; for he is an omnipotent, omniscient, and unchangeable Being, and neither frustrates, nor is he frustrated; nor is there any insincerity, unrighteousness, and unfaithfulness in him; nor can he act contrary to himself, and the perfections of his nature: the way also which he prescribes to others is perfect and plain, whether the path of doctrine or of duty; the path of truth is plain to the enlightened understanding, and the way of holiness is such, in which men, though fools, shall not err; see Proverbs 8:8;
the word of the Lord is tried; as silver in a furnace, and is clear of all dross, of error, and falsehood; is free from human mixtures, and without any impurity and unholiness; nor is God's word of promise chargeable with unfaithfulness; all his promises being yea and amen in Christ, and have been tried and proved by the saints in all ages; and have been found true, faithful, constant, and invariable;
he [is] a buckler to all those that trust in him; not in man, nor in themselves; in their own righteousness, or in any creature or creature enjoyment or performance; but in the providence and power of God, in his grace and mercy, in his word, and especially in his Son; in his person, blood, and righteousness; to such he is a buckler or shield: his power is all around them, his favour encompasses them, and his truth, or faithfulness in his word, is their shield and buckler: and so is his Son, who is both a sun and shield to them; and such are his precious blood, his spotless righteousness, and stoning sacrifice; which, being held up by faith, repel the fiery darts of Satan.
m תמים αμωμος, Sept. "impolluta", V. L. so Syriac. Aethiop.