Thou shalt be saved. To confess the Lord Jesus, and to call upon the name of the Lord, (ver. 13.) is not barely the professing of a belief in the person of Christ: but moreover implies a belief of his whole doctrine, and an obedience to his law; without which the calling of him Lord will save no man. (St. Matthew vii. 21.) (Challoner)
This passage must be understood like many others of this apostle, of a faith accompanied by a good-will ready to perform what faith says must be practised; as it is required in this very place, that what we believe in the heart, we should confess with our mouth. (Estius)
Then he continues, "If thou shall confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised Him from the dead, thou shall be saved."