The warnings in scripture given in the context of the visible church are directed at both the regenerate and unregenerate, both wheat and tares, both sheep and goats. These kind of warnings serve two purposes:
1) The elect (sheep) hear his voice in the word and take heed.
2) The non-elect (goats) do not hear his voice and fall away.
In other words, the warnings serve as a means of grace (or hardening). - when the elect hear warnings in scripture it causes them to persevere. When the non-elect hear it, their heart hardens over time and they fall away completely, revealing that they have been trusting in something other than Christ alone for salvation.