For he that is not against us is for us. In St. Matthew (Matthew 12:30) we find our Lord using a somewhat similar expression, only in an inverted order. He there says, "He that is not with me is against me."
The lesson which both these apothegms teach is the same, that there is no such thing as neutrality in reference to Christ and his cause. We must be either with him or against him. Dr. Morison on St. Mark in this place says, "When in applied morals we sit in judgment on ourselves, we should in ordinary circumstances apply the law obversely and stringently,' he who is not with Christ is against him.'
But when we are sitting in judgment on others, into whose hearts we cannot look directly, we should in ordinary circumstances apply the law reversely and generously, ' He that is not against Christ is with him.'