Thirdly, Obedience is necessary, though not to the first entrance into justification, yet to the continuance of it; not indeed as a cause, but as a condition. Thus Bishop Davenant, Bona opera sunt necessaria ad justificationis statum retinendum et conservandum; non ut causae, quae per se efficiant aut mereantur hanc conservationem; sed ut media seu conditiones, sine quibus Deus non vult justificationis gratiam in hominibus conservare. If a believer, who is instantly justified upon believing, would continue justified, he must sincerely obey God. Though his obedience in measure and degree reach not fully to the precept of the gospel; yet in truth and substance it comes up to the condition of it; else he cannot continue justified; this to me is very evident; we are at first justified by a living faith, such as virtually is obedience; and cannot continue justified by a dead one such as operates not at all. We are at first justified by a faith which accepts Christ as a Saviour and Lord; and cannot continue justified by such a faith as would divide Christ, taking his salvation from guilt, and by disobedience casting off his lordship; could we suppose that which never comes to pass, that a believer should not sincerely obey: How should he continue justified? if he continue justified, he must, as all justified persons have, needs have a right to life eternal; and if he have such a right, how can he be judged according to his works? no good works being found in him after his believing, how can he be adjudged to life? or how to death, if he continue justified? These things evince, that obedience is a condition necessary as to our continuance in a state of justification: nevertheless it is not necessary, that obedience should be perfect as to the evangelical precept; but that it should be such, that the truth of grace which the evangelical condition calls for, may not fail for want of it: “Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city,” (Rev. xxii.14.) The first fundamental right to heaven they have by the faith of Christ only: but sincere obedience is necessary that that right may be continued to them: in this sense we may fairly construe that conclusion of St James, “Ye see, then, how that by works a man is justified, and not by faith only,” (Jam. ii.24.) Faith brings a man into a justified estate; but may he rest here? No, his good works must be a proof of his faith, and give a kind of experiment of the life of it. Nay, they are the evangelical condition, upon which his blessed estate of justification is continued to him; in foro legis, Christ and his righteousness is all; neither our faith nor our works can supply the room of his satisfaction to justify against us against the law: but in foro gratiae, our obedience answers to the evangelical condition, and is a means to continue our justified estate: it is true, St. Paul asserts that we are justified by faith, not by works, (Rom iv.); which seems directly contrary to that of St. James, that a man is justified by works, not by faith only. But the difference is reconciled very fairly, if we do but consider what the works are in St. Paul, and what they are in St. James. In St. Paul, the works are pefect works, such as correspond to the law, such as make the reward to be of debt, (ver. 4.) Hence Calvin saith, “Operantem vocat, qui suis meritis aliqui promeretur, non operantem, cui nihil debetar operum merito.” In St. James, the works are sincere only, such as answer not to the law, but to the evangelical condition; such as merit not, but are rewarded out of grace. Works in St. Paul, are such as stand in competition or co-ordination with Christ and his righteousness, which satisfied the law for us. Works in St. James are such as stand in due subordination to Christ and his righteousness, and are required only as fruits of faith, and conditions upon which we are to continue in a justified state.
~A View of Some Divine Truths pg. 92-93