John Gill's Bible Commentary Ver. 2. For I bear them record, that they have a zeal of God , etc..] A zeal for God; for the being and unity of God, against the polytheism and idolatry of the Gentiles; for the word of God, the writings of the Old Testament, of which they were zealous defenders and preservers, and which they diligently read and heard explained, and whereby they thought to obtain eternal life; for the law of God, moral and ceremonial, especially for the rituals of the Mosaic economy; for the service and worship of God, they spared no pains, but compassed sea and land to bring in proselytes to their religion; all which the apostle could testify from his own knowledge, and by his own experience, who had been as great a zealot as any of them all. But now whilst the apostle is expressing his strong affection for this people, he is careful to act the faithful part to them, and points out their mistakes, and shows them their faults; which he does in this and the following verse, by observing, that they had a zeal of God indeed, but not according to knowledge : it was not well regulated, it proceeded on mistaken principles, and moved in a wrong way, in persecuting the church of God, in doing things contrary to the name of Christ, in putting to death his ministers and members, thinking that hereby they did God good service; which arose from their ignorance of their Father, and of the Son: though they had a zeal of God, they knew neither God nor Christ aright; they did not know God in Christ, nor Jesus to be the true Messiah; they understood neither law nor Gospel truly, and fancied the Gospel was contrary to the law, and an enemy to it; and therefore in their great zeal opposed it, and the professors of it; they were zealous of the law, and of doing the commands of it, but knew not the true nature, use, and end of the law; as appears by what follows.
Matthew Henry Commentary
Verses 1-4 - The Jews built on a false foundation, and refused to come to Christ for free salvation by faith, and numbers in every age do the same i various ways. The strictness of the law showed men their need of salvation by grace, through faith. And the ceremonies shadowed fort Christ as fulfilling the righteousness, and bearing the curse of the law. So that even under the law, all who were justified before God obtained that blessing by faith, whereby they were made partakers of the perfect righteousness of the promised Redeemer. The law is no destroyed, nor the intention of the Lawgiver disappointed; but ful satisfaction being made by the death of Christ for our breach of the law, the end is gained. That is, Christ has fulfilled the whole law therefore whoever believeth in him, is counted just before God, as muc as though he had fulfilled the whole law himself. Sinners never coul go on in vain fancies of their own righteousness, if they knew the justice of God as a Governor, or his righteousness as a Saviour.
Greek Textus Receptus
μαρτυρω 3140 5719 V-PAI-1S γαρ 1063 CONJ αυτοις 846 P-DPM οτι 3754 CONJ ζηλον 2205 N-ASM θεου 2316 N-GSM εχουσιν 2192 5719 V-PAI-3P αλλ 235 CONJ ου 3756 PRT-N κατ 2596 PREP επιγνωσιν 1922 N-ASF
Vincent's NT Word Studies
2. I bear them record (marturw). Rev. witness. "He seems to be alluding to his conduct of former days, and to say, 'I know something of it, of that zeal'" (Godet).Zeal of God (zhlon Qeou). Rev., zeal for God. Like the phrase "faith of Christ" for "faith in Christ" (Philip. iii. 9); compare Col. ii. 12; Eph. iii. 12; John ii. 17, "the zeal of thine house," i.e., "for thy house." Knowledge (epignwsin). Full or correct and vital knowledge. See on ch. i. 28; iii. 20.
Robertson's NT Word Studies
10:2 {A zeal for God} (zlon qeou). Objective genitive like #Php 3:9, "through faith in Christ" (dia pistews cristou). {But not according to knowledge} (all' ou kat' epignwsin). They had knowledge of God and so were superior to the Gentiles in privilege (#2:9-11), but they sought God in an external way by rules and rites and missed him (#9:30-33). They became zealous for the letter and the form instead of for God himself.