When people had obedient faith, they were always justified—or saved—by God via the blood of Christ (Heb. 9:15; Rom. 3:24-25). You ought to tremble like the demons/devils if you have faith but disobey (Jms 2:19). Is it possible for a faith that believes in God but lacks a faith of obedience to the will of God to save? The devils tremble, but why? Although they do believe, they are disobedient. A faith devoid of submission to God will not be saved (Matt. 7:21). From what will his faith save him from (Jms 2:19)? The judgment of man? Are people of faith more concerned that we tremble at the judgment of MAN with our SOULS? The disobedient, however, should have that fear where they tremble (like the demons do), of the judgment of God (Matt. 10:28; Lk. 12:4-5; Heb. 10:31; etc etc).
In contrast, those who are in Christ and abide in Him should have no fear when it comes to our soul. (Rom. 8:38-39). James 2 is about being justified in the sight of God by having an obedient faith that submits to His will. In verses 15-17, James points out that a faith that just pays lips service but doesn’t act, is dead (v15-17). He then goes on to bring up two Old Testament examples so that we can learn what kind of faith and works justifies/saves (Gen. 22:1-12; Jos. 2:15-21; Rom. 15:4; 1 Cor. 10:11). Abraham and Rahab had a faith that was justified by works of faith/obedience to the will of God. Instead of having a heart that was far from Him (Matt. 15:8; Mk. 7:6; Is. 29:13), both Abraham and Rahab expressed how they had a heart near to Him by having a working faith. The kind of faith one needs to have is a working faith to the will of God. In contrast, a dead faith that is not centered on doing the will of God cannot and will not save.