According to the sermon, what is a constant threat to all human beings?

Edwards
defines human "wickedness" as a constant threat to all human beings.  This condition
is what invokes God's anger and is what Edwards sees as the fundamental threat in being in the
world.  For Edwards, the basic condition of wickedness that is intrinsic to human beings is that
against which God directs his anger against:

So that it is
not because God is unmindful of their wickedness, and does not resent it, that he does not let
loose his hand and cut them off. God is not altogether such an one as themselves, though they
may imagine him to be so. The wrath of God burns against them, their damnation does not slumber;
the pit is prepared, the fire is made ready, the furnace is now hot, ready to receive them; the
flames do now rage and glow. The glittering sword is whet, and held over them, and the pit hath
opened its mouth under them.

Edwards sees the threat of
wickedness present in those who knowingly turn from God's grace and power.  He also sees it in
those who are "spiritually somnolent."  Edwards seeks to awake these individuals for
their actions cause God great anger, and thus pose a constant threat to individual salvation.
 It is here in which righteousness is defined in a clear manner:  One must be aware of and
demonstrate embrace towards the power of God.  One cannot live in slumber and expect God to not
take action against them.  "The hearts of damned souls" contain a level of
"wickedness" that causes God to be filled with great anger.  It is this condition of
being that Edwards identifies as critical to the spiritual awakening of humanity.  It is
critical to avoid the fate of condemnation from the divine.  Aspects of this include the
"rejection" of the divine in the form of God and Christ.  When this happens,
wickedness is present and this becomes the constant threat to all human
beings.