Since I am not a Calvinist my presuppositions are far less of this I am quite sure.
Define enemy?
Don't worry you will have as many presuppositions as anyone else. We can easily deceive ourselves.
Enemy -
For behold, your enemies, O LORD, for behold, your enemies shall perish; all evildoers shall be s scattered. Psalm 92:9
The mind governed by the flesh is hostile to God; it does not submit to God’s law, nor can it do so. Those who are in the realm of the flesh cannot please God. Rom 8:7
As far as the gospel is concerned, they are enemies for your sake; but as far as election is concerned, they are loved on account of the patriarchs Rom 11:28.
For, as I have often told you before and now tell you again even with tears, many live as enemies of the cross of Christ. Their destiny is destruction, their god is their stomach, and their glory is in their shame. Their mind is set on earthly things. Philippian 3:18f
And the list goes on. I am refering here to the human enemy those who are not saved. But there are other enemies Satan etc even death itself.
The good thing is, as John reminds us:
For God so loved the world, 9 that he gave his only Son, that whoever believes in him should not perish but have eternal life. 17For God did not send his Son into the world m to condemn the world, but in order that the world might be saved through him. 18 Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God. John 3:16ff.
And while wenwerenyet still enemies, christ dies for us.. The us being those in christ.