Perhaps a more focused starting point in an effort to engage an understanding of “pacifism” is to define “separate”... as in separate from the world. How we define this disconnect from the world will better enable us to put meaning as to the role of a Christian in a fallen world.
In defining terms would we agree that “World” is best confined to humanity? The contrasts in 2 Cor. 6:14-17 are of human characteristics/behavior – righteousness vs. wickedness, light vs. darkness, believer vs. unbeliever, etc. So though we are in the world (relative to sinful pursuits and perspective) we are not of the world, our allegiance is to God through Christ Jesus in terms of our conduct and commitment to “holiness”. Those who claim Christ are set apart, not physically but spiritually.
Does this suggest that we disengage completely from the world? 1 Cor. 5:9-10 would suggest otherwise and support that what is being referred to in “separate” is behavioral not physical as noted above.
Mark 2:15-17 clearly illustrates our role in the world. Further, the “great commission” (Matt. 28:19-20) has Christ commanding the role of the Christian in the world. Obviously then we are separate in our worldview/conduct/behavior but we are to engage people which requires our physical presence. Christianity is centrifugal not centripetal. (GKC)
Christ not only included the outcasts, sinners, and the unwanted of society but He loved them. I would suggest that there does exist both conceptually and in reality as demonstrated by Christ, human dignity. If all those without God can be considered enemies, and we are commanded to love them, then again there exists in the eyes of Christ human dignity.