But if that was the case roughly 2000 years ago, what makes us so sure that it is not the case today?
Yes and we see it all the time. Especially on the topic of hell. The Bible says hell is anywhere that God is not. All the hellfire and brimstone and descriptions of what hell is, is man's attempt to describe what THEY THINK things look like when God isn't present. So yeah, its absolutely the case today. Personally, I prefer to take the "wait and find out" approach.
I believe that is ultimately a third of the question. The other third is why does God allow his people to go off on such a tangent? And the final third would be those concerning the historically nasty fight with horrific consequence some to this day for ownership of the Jewish scriptures.
I'm of the belief that God does everything he does with an eye on creating curiosity in us to seek him. I believe that's why the three elements of worship are the way they are. The Bible is there to give us A LOT of insight. The Holy Spirit is there for us to reach out to with our "God, where are you? Am I doing this right?" kinds of questions/conversations. Communion with others is there because we are incredibly social creatures and have a lot to offer each other on this journey while on earth.