If justice is only an implication, it can easily become optional and, especially in privileged churches, non-existent. In the New Testament, conversion happens in two movements: Repentance and following. Belief and obedience. Salvation and justice. Faith and discipleship.
Atonement-only theology and its churches are in most serious jeopardy of missing the vision of justice at the heart of the kingdom of God. The atonement-only gospel is simply too small, too narrow, too bifurcated, and ultimately too private.