An anti-Calvinist friend of mine presented the following argument:

Calvinist can’t know they are saved because they don’t know if they were elect or not. Assurance is only obtainable if universal atonement is true. The Bible doesn’t say that you are elect.

I think that this argument doesn’t work:

i) That’s not a strong argument. The objection cuts both ways. How do you know you have saving faith? The Bible doesn’t say that anyone in the 20th and 21st centuries had or have faith. This system ends up with the same problems Clarkians have.

ii) The other factor is that Romans 8:16 answers this. It gives the mechanism for our assurance. The scriptures tell us that these writings contain what we need in order to have faith.

iii) You may respond that in history many of those that seemed to be Christians turned out to be apostates. That response doesn’t seem correct. Dr. James Anderson said:

It’s not clear to me what your argument is here. I’m guessing it’s one or other of the following:

A1: Some Christians apostatize. Therefore, no Christian can know that he’s saved.

A2: Some people who are convinced that they’re Christians apostatize. Therefore, no Christian can know that he’s saved.

A1 obviously begs the question against the Calvinist. So that’s a non-starter.

A2 is a non-sequitur. Nothing much significant about the possibility of assurance follows from the uncontroversial fact that some people who are convinced they’re Christians later apostatize — unless one imports implausibly strong assumptions about the necessary conditions of knowledge. But apparently you want to disavow such assumptions. So how else will you support the crucial inference in A2?

Look at it this way. Suppose I were to offer this argument:

A3: Some men who are convinced that they’re the fathers of children living in their homes turn out not to be. Therefore, no man can know that he’s the father of a child living in his home.

You would be right to laugh at such an argument. But it’s no different in form than A2; and it’s fallacious for the same reason.

Now, you might claim that the Calvinist’s doctrine of assurance is making a stronger claim than that a Christian can know that he’s saved. But different Calvinists have interpreted the doctrine in different ways. So you’ll need to be more specific about which interpretation you mean to target.

Perhaps you’ll say you’re targeting the view that a Christian can know with certainty that he is saved. But epistemologists commonly distinguish various kinds of certainty (e.g., psychological certainty, maximal justification, maximal warrant, indubitability). Calvinists aren’t obviously committed to one particular interpretation here. So again, you’ll need to be more specific about your target (and the relevance of that target with respect to mainstream Calvinist theology).

In short, your argument, as it stands, doesn’t have a whole lot going for it. It’s mired in ambiguity and hamstrung by reliance on dubious epistemological assumptions.