Salvation through faith alone, a defining doctrine of Protestantism. But it's not really one doctrine, since it seems to be understood in multiple ways. Broadly, I see two versions of it here. The first one is not really objectionable, it is simply this: you are saved solely through faith, salvation being a gift and not something you can earn or be worthy of; however, if your faith does not engender works, it is a "dead faith", not a living faith. Because if you were filled with true faith, works would grow (super)naturally from that (Matthew 7:18).
Then there is this other version of the doctrine, which identifies all works as "works of the law" (that is, the law of life and death, the law of sacrifice, the law of the fall, the law of the old covenant, the law of circumcision that Paul said was done away with). This version, perversely, equates all moral injunctions of the New Testament, with those of the Mosaic Covenant: as unnecessary with Christ. I see proponents of this say, for instance, that fornication is no longer a big deal, so long as you have faith. And whether or not your faith engenders works is irrelevant.
The second versions seems Satanic to me. Doing away with circumcision and eating Kosher, doesn't mean doing away with morality altogether. It means morality is no longer in an eye-for-an-eye, sacrificial framework, but rather in the framework of God's grace making it possible for you to become his vessel and through His Spirit's guidance do good works. But you actually have to submit yourself to the Holy Spirit; if you just ignore Him and continue to disregard His grace, that's not Christian at all. Yes, we are all sinners, but that is precisely why we must be contrite, mournful, in great sorrow over our sins, like the Publican who beat his breast, like the woman who washed Christ's feet with her tears; just saying, "Yessirree, I sure do sin," there's something wrong with that. There is no contrition in that at all.
Then there is this other version of the doctrine, which identifies all works as "works of the law" (that is, the law of life and death, the law of sacrifice, the law of the fall, the law of the old covenant, the law of circumcision that Paul said was done away with). This version, perversely, equates all moral injunctions of the New Testament, with those of the Mosaic Covenant: as unnecessary with Christ. I see proponents of this say, for instance, that fornication is no longer a big deal, so long as you have faith. And whether or not your faith engenders works is irrelevant.
The second versions seems Satanic to me. Doing away with circumcision and eating Kosher, doesn't mean doing away with morality altogether. It means morality is no longer in an eye-for-an-eye, sacrificial framework, but rather in the framework of God's grace making it possible for you to become his vessel and through His Spirit's guidance do good works. But you actually have to submit yourself to the Holy Spirit; if you just ignore Him and continue to disregard His grace, that's not Christian at all. Yes, we are all sinners, but that is precisely why we must be contrite, mournful, in great sorrow over our sins, like the Publican who beat his breast, like the woman who washed Christ's feet with her tears; just saying, "Yessirree, I sure do sin," there's something wrong with that. There is no contrition in that at all.