Just as the spirit joins itself to the body and by doing so brings the latter to life, so works, joined to faith, give life to it as well. Furthermore, it is to be understood that faith without works is not faith at all, just as a dead man is not really a human being. But how can some say that because the spirit which gives life to the body is more honorable than the body, therefore works are more honorable than faith? I have looked into this matter in some detail and shall try to explain my position on this. It is undoubtedly true that the spirit is nobler than the body, but this does not mean that works can be put before faith, because a person is saved by grace, not by works but by faith. There should be no doubt but that faith saves and then lives by doing its own works, so that the works which are added to salvation by faith are not those of the law but a different kind of thing altogether. (Commentary on James)
Faith without works is dead, and works without faith are dead also. For if we have sound doctrine but fail in living, the doctrine is of no use to us. Likewise if we take pains with life but are careless about doctrine, that will not be any good to us either. It is therefore necessary to shore up the spiritual edifice in both directions. (Sermons on Genesis 2.14)
James is talking here about faith after baptism, for a faith without works can only make us more guilty of sin, seeing that we have received a talent but are not using it profitably. The Lord himself demonstrated the need for works after baptism by going into the desert to do battle with the devil. (Mt 4:1-11) Paul also exhorts those who have entered into the mystery of faith to "strive to enter his peace," (Heb 4:4) as if faith by itself were not enough. Holiness of life is also necessary, and for that great efforts are required.