JMNT(i)
16 Within this we have come to know the Love (acceptance which drives to overcome estrangement and achieve reunion) by intimate experience: that That One placed (or: places; sets; deposited) His soul over us; we ourselves are also constantly indebted (obligated) to place [our] souls over the brothers (= fellow believers, or, fellow humans; = [God’s] family).
17 But whoever may continuously have the world's means of living (or: may habitually hold the sustenance of the life pertaining to the secular ordered System), and may habitually gaze upon his brother [who is] continuously having a need, and may close shut (or: would slam and lock) his intestines (= his compassions) away from him, how is God's love dwelling (abiding; remaining; staying) within him (or, reading as a future: how will God's love dwell in him)?
18 Little children (little born-ones), we should not be habitually loving in word (by a word or thought), nor even in (or: by) the tongue, but rather within action (deed; work) and truth (or: reality).