Vincent's NT Word Studies
5. Believeth on Him (pisteuonti epi ton). The verb pisteuw to believe is used in the New Testament as follows: 1. Transitively, with the accusative and dative: to entrust something to one, Luke xvi. 11; John ii. 24. In the passive, to be entrusted with something, Rom. iii. 2; 1 Cor. ix. 17; Gal. ii. 7. With the simple accusative, to believe a thing, John xi. 26; 1 John iv. 16.
2. With the infinitive, Acts xv. 11.
3. With oti that, Matt. ix. 28; Mark xi. 24; Jas. ii. 19. Especially frequent in John: iv. 21; xi. 27, 42; xiii. 19; xiv. 10, 11; xvi. 27, 30, etc.
4. With the simple dative, meaning to believe a person or thing, that they are true or speak the truth, John ii. 22; iv. 21; v. 46. See on John i. 12; ii. 22, 23; viii. 31; x. 37.
5. With the preposition ejn in. Not frequent, and questioned in some of the passages cited for illustration. In John iii. 15, ejn aujtw in Him, is probably to be construed with have eternal life. The formula occurs nowhere else in John. In Mark i. 15 we find pisteuete ejn tw eujaggeliw believe in the gospel. The kindred noun pistiv faith, occurs in this combination. Thus Gal. iii. 26, though some join in Christ Jesus with sons. See also Eph. i. 15; Col. i. 4; 1 Tim. iii. 13; 2 Tim. iii. 15; Romans iii. 25. This preposition indicates the sphere in which faith moves, rather than the object to which it is directed, though instances occur in the Septuagint where it plainly indicates the direction of faith, Psalm lxxvii. 22; Jer. xii. 6.
6. With the preposition ejpi upon, on to, unto.
a. With the accusative, Rom. iv. 5; Acts ix. 42; xi. 17; xvi. 31; xxii. 19. The preposition carries the idea of mental direction with a view to resting upon, which latter idea is conveyed by the same preposition.
b. With the dative, 1 Tim. i. 16; Luke xxiv. 25; compare Romans ix. 33; x. 11; 1 Pet. ii. 6. The dative expresses absolute superposition. Christ as the object of faith, is the basis on which faith rests.
7. With the preposition eijv into, Matt. xviii. 6; John ii. 11; Acts xix. 4; Rom. x. 14; Gal. ii. 16; Philip. i. 29, etc. The preposition conveys the idea of the absolute transference of trust from one's self to another. Literally the phrase means to believe into. See on John i. 12; ii. 23; ix. 35; xii. 44.
Is counted for righteousness (logizetai eiv dikaiosunhn). Rev., is reckoned. See on ver. 3. The preposition eijv has the force of as, not the telic meaning with a view to, or in order that he may be (righteous); nor strictly, in the place of righteousness. Faith is not a substitute for righteousness, since righteousness is involved in faith. When a man is reckoned righteous through faith, it is not a legal fiction. He is not indeed a perfect man, but God does not reckon something which has no real existence. Faith is the germ of righteousness, of life in God. God recognizes no true life apart from holiness, and "he that believeth on the Son hath life." He is not merely regarded in the law's eye as living. God accepts the germ, not in place of the fruit, but as containing the fruit. "Abraham believed God.... No soul comes into such a relation of trust without having God's investment upon it; and whatever there may be in God's righteousness - love, truth, sacrifice - will be rightfully imputed or counted to be in it, because, being united to Him, it will have them coming over derivatively from Him" (Bushnell). The idea of logical sequence is inherent in logizetai is reckoned - the sequence of character upon faith. Where there is faith there is, logically, righteousness, and the righteousness is from faith unto faith (ch. i. 17). Nevertheless, in the highest development of the righteousness of faith, it will remain true that the man is justified, not by the works of righteousness, which are the fruit of faith, but by the faith which, in making him a partaker of the life and righteousness of God, generates and inspires the works.
Observe that the believer's own faith is reckoned as righteousness. "In no passage in Paul's writings or in other parts of the New Testament, where the phrase to reckon for or the verb to reckon alone is used, is there a declaration that anything belonging to one person is imputed, accounted, or reckoned to another, or a formal statement that Christ's righteousness is imputed to believers" (President Dwight, "Notes on Meyer").
Robertson's NT Word Studies
4:5 {That justifieth the ungodly} (ton dikaiounta ton asebe). The impious, irreverent man. See #1:25. A forensic figure (Shedd). The man is taken as he is and pardoned. "The whole Pauline gospel could be summed up in this one word-- God who justifies the ungodly" (Denney).