Is salvation by grace, or by works? A Christian will answer grace, but there are many false religions that will actually answer "yes". Every works based gospel, at least as far as I have studied, claims to believe salvation is by grace. Catholics claim to believe salvation is by grace. Mormons claim to believe salvation is by grace. Jehovah's Witnesses claim to believe salvation is by grace. These three religions all claim to be Christianity, even the one true Church, yet in their "gospels", salvation requires a certain amount of works from the believer. But still they claim salvation is by grace.
As shown in the header image, the most expensive car to be sold at auction was a 1962 Ferrari 250 GTO. This car was sold by RM Sotheby's auction house for a whopping $48.4 million. This car, safe to say, was not free. You cannot sell something for free. If you sell it, it's not free. If it's free, you did not sell it.
This actually reminds me of a time as a child when some girls were having a "bring and buy" sale in the street just outside my house. They were selling their old toys, and they had an offer: "Buy one, get one free". But this had a condition. If you paid 10p, you only got one toy. If you paid 20p, they applied the "buy one, get one free" offer. To my 8 year old mind, this sounded amazing. I get a free toy if I... pay for it? In my adult mind, I see that I was scammed. I didn't buy one and get one free, I bought 2 and got none free.
Such is the case with works based "gospels." Aside from the fact they don't actually work, it wouldn't be grace if they did. If you earn your way to Heaven, God didn't save you by grace, He gave you what He owed you. Even if we alter my analogy so I only had to pay an extra 5p to get the offer, that's still not buying one and getting one free, it's buying one and getting another at a half price discount. Similarly, if salvation is only partially by works, it is still not grace plus works, just as a discount is not free plus payment.
Grace, by definition, is the opposite of works. We can even prove this from the Bible, because God directly defines His terms. Aside from referring to salvation as a gift, we actually have a "dictionary verse" in the form of Romans 11:6. From the NABRE, which I feel the need to point out is a Catholic translation (i.e. the translators are biased against the idea that grace is the opposite of works), we read "But if by grace, it is no longer because of works; otherwise grace would no longer be grace." Let me repeat that: if by grace, it is no longer because of works; otherwise grace would no longer be grace. Based on some manuscripts, some translations, such as the KJV, render it: "And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then it is no more grace: otherwise work is no more work."
So we see that the Bible explicitly defines grace as the opposite of works. This is further backed by the more famous grace verse Ephesians 2:8-9, which says "For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast." (NKJV, emphasis mine).
Without some rather painful mental gymnastics, it is impossible to interpret salvation as being obtained by both grace and works. If you believe salvation is by grace, you cannot believe it is by works. If you believe it is by works, you cannot believe it is by grace. This means that any religion that holds to a works based "gospel", such as the ones mentioned above, are lying in two ways. First, they are lying because they claim salvation requires works. By altering the Gospel in this way (or indeed, at all), they are anathema (Galatians 1:8). Second, they are lying because they claim to believe salvation is by grace, yet as we have seen, they actually cannot believe that, by definition.
Followers of false, works based gospels need to repent immediately. The Bible makes it quite clear that if we ask Jesus to judge our works, He will, and as we are all sinners, this is not something we want. If, however, we want His grace, it is required that we obtain it through faith. Not faith in our works, but faith in His. As with any gift, the cost is not paid by the recipient. If salvation is, as Ephesians tells us, the gift of God, the price must be paid by God. What do you think the cross was? The only works required for our salvation were performed nearly 2,000 years ago by none other than Jesus Christ, after which He confidently declared "it is finished". That, my friends, is what grace is.