Catholics believe that you attain salvation by faith, baptism, and observance of the commandments (CCC 2068). Whereas Evangelicals believe that salvation is received by grace alone through faith alone in Christ alone apart from works. We can’t both be right. Therefore, we should respectfully dialogue about topics like these.
And…this is an example of how not to dialogue. You claimed that “Catholics and Protestants cannot both be Christians,” and since you’re Protestant, that obviously gives the implication to Catholics that we aren’t Christian. Once digging in, though, it becomes obvious that you don’t fully understand the Catholic position. Part of what I meant when saying that we should understand each others’ positions is to avoid reducing the others’ position, and you should especially avoid making such offensive claims unless you are 100% sure that you
fully understand their position.
But to delve a bit deeper: Bear in mind that Catholics have a lot more to say about justification, grace, and merit than one paragraph in the CCC that quotes Vatican II. For instance, we recognize that “no man can inherit the initial grace of forgiveness and justification” (CCC 2010) and that we can never merit God’s favor on our own but that it is God’s desire to associate
His works and merit with us (CCC 2006-2010). Furthermore, God’s grace is entirely free of anything we do (CCC 1996) and even our move to receive it is an act of grace on His part (CCC 2001), and this includes sacraments like baptism (CCC 2003).
Basically, we would agree in “grace alone…in Christ alone”. If you want to get down into nuances, we may even agree on “apart from works”, in that we agree that we cannot perform any work to merit God’s grace. The major hangup, and where we would disagree with “faith alone”, is that we believe man must respond to God’s grace (CCC 2002), because God won’t force grace on anyone. While the actual preparation to receive this is itself an act of grace (CCC 2001), our need to act - or work - cannot be ignored. However, you should
not, as so many Protestants claim, see this as us trying to get God to give us His grace. He’s already offering it and pouring it out for all to receive whether they choose to receive it or not. Works only come into play when we are talking about our need to freely receive this grace already being offered. It’s less working for a wage and more receiving a gift rather than throwing it away.
Sure, this still leaves open dialogue about the merits (pun not intended) of
sola fide. But I think this covers a bit of why you shouldn’t be reductionistic, because you can get way off of what the each side actually believes.