A society would do well to allow military deferments for a season to certain ones, but exclude from military service those who are full of fear and anxiety as such will spread through the troops and spoil the heart and mind of many.
Those IN CHRIST who are full of fear - doubting God's Word - when it comes to doing spiritual battle can detract others from believing God and acting in faith and obedience.
Some unsaved peoples blindly (no real or reasonable reason) fear the multiplication of Christ-followers - therefore, it must be satan's destructive purposes (unseen) moving the unsaved peoples.