2nd Chronicles 5:14–> Why does the smoke/glory of the Lord cause the priest’s ministry to stop?
Having never experienced the presence of the glory of the LORD in this way, I can only speculate. But it would seem that the glory of the LORD is rather like a fire. Imagine a normal building giving off as much smoke as the temple was apparently giving off at this time. That much smoke would have to be the result of a very significant fire. If the temple had been on fire that fiercely, no one could have gone into it to minister because of the heat of the flames.
Now of course the temple was not on fire, and so there was no heat. Yet the glory of the LORD was producing this smoke, and there seems to have been something about that glory that had the same effect. If one would approach a blazing building, one could feel the heat, and realize that to enter this building at this time would result in death. Though it is hard to know exactly how it worked, it seems that the glory of the LORD somehow had the same effect. If the priests were to walk toward the temple, they could somehow “feel” that to enter it would mean death, just as if it really were on fire. What they felt or how they knew this, I do not know.
That said, that is just how I picture it. I suppose one could imagine that it was just that somehow God communicated this to them, perhaps through one inspired to tell them this, and so they knew they couldn’t approach the temple because of some message they received. But there is no mention of such a thing in the passage. I tend to just think that God’s glory has that effect on men. It cannot be approached, at least, not without much strengthening on the part of God Himself. However it happened, the priests were simply unable to approach a building that was blazing with God’s presence.