Folks tend to have a hard time wanting to agree, but will find it hard to disagree on this idea. Not because it’s particularly interesting, and not because it is an attack on any specific belief, but that it asks them to think about belief and follow through to what the implications are.
So if the theory of “belief” we have that states belief entails action, rather than just an attitude toward some state of affairs, then you have to examine what this means for religious doctrine. For example, to say “I believe there is a God”, we mean there exists an idea upon which I can and will act. We should apply that to the various creeds we have in Christianity.
“I believe Jesus is the Son of God” or “I believe in the Trinity” are examples we can ask about. If there is any credal statement which is an assertion to be “believed” but the assertion is not actionable, we have to ask whether or not it is true that all proper beliefs entail action. I think there are grounds to disagree and that these are certainly counter-examples that would make the point. But, that’s not the problem. The problem is that when we say “I believe Jesus is the Son of God” and that this is not an actionable belief, we have unmistakenly agreed that this belief is not and cannot be any kind of cental, important, or significant aspect of Christian belief; that is, aside from the function those beliefs have within, and only within, a particular Christian community that binds them together.
Suppose however, that we don’t want to deny this theory of “belief” and then can say such ideas as “Jesus is the Son of God” are in fact, actionable. If we can, then we can indeed say that such credal statements are perhaps central and necessary. Does this preserve the idea that they are?
If it turns out that we say “Because I believe Jesus is the Son of God … I follow his teachings”, then we have a start. But if it also turns out that “I do not believe Jesus is the Son of God … but for some other reason, I follow his teachings”, then “Jesus is the Son of God” cannot be seen as a central, necessary belief of Christianity.
Whether credal statements are or are not actionable, we can only say that they are significant to a particular community of believers, but never that such statements define Christian beliefs. Why? Because undoubtedly, the only actionable and proper beliefs about Christ we can hold are his teachings themselves. For if we take a creed as non actionable, we have said it is of literally no epistemic value since there is nothing to act upon, and if we take a creed as actionable, the centrality of the creed is only relative to any particular community of believers that think it is important to their community.
The obvious implication is that proper Christian beliefs, those that are central, that do matter in any epistemological sense, are the teachings of Christ and that the only consistent thing to say about salvation or atonement is that Christ lives anywhere the good is done, which is through the work of the Holy Spirit, and the good being what we as Christians, in faith, name “God”. Directly as a consequence, we have no right to suggest an Atheist, a Muslim, a Jew, or anyone else is not a Christian when they themselves can and do embody Christ through their works (James 2:14-26).