This is an unhappy expression, bringing in the name of God where it does not occur. In the O.T. it is chalilah, 'far be it.' Ge 44:7,17, etc. In the N.T. ?? ???????, 'let it not be.' Ro 3:4,6,31, etc.
God must prove true, though every man prove a liar! As Scripture says of God-'That thou mayest be pronounced righteous in what thou sayest, and gain thy cause when men would judge thee.'
Do we, then, use this faith to abolish Law? Heaven forbid! No, we establish Law.