It’s a good quote by Justin Martyr. I’ve read it myself.
However, there is one caution. There is no place that Justin indicates that the “other view” is amillennialism or preterism or post-millennialism.
In fact, in context one would really think that the “other view” could also be pre-millennial but with some differences in either sequences or locations.
Good point. But it still seems, IMO, to suggest that disagreements over the interpretation of biblical prophecy shouldn't necessarily be a cause to doubt anyones salvation or think of them as anything other than brothers and sisters in Christ. (though I'm always of the opinion that each should look to their own salvation and not anyone elses!)