I have heard the idea that there is wisdom (such as science) by the non-Jews, but there isn’t Torah by non-Jews. There are Christians who study the Bible and know it well, why isn’t this considered to be Torah amongst the non-Jews?

There's more than one way to resolve your conflict, it depends what we mean when we say Torah. I will go in one path though there are more ways of explaining. This verse ("Torah Bagoim Al Taamin" = there's no Torah in the gentiles; Eicha Raba 2) comes to speak about the Jewish wisdom and non Jewish or secular wisdom and just comes to say that the Torah – the Jewish teachings are from a divine source and qualify the term "Torah" as appose to the secular wisdoms and teachings which may be brilliant but not divine – to say – not teaching of Godliness and therefore not "Torah".