That we may obtain this faith, the Ministry of Teaching the Gospel and administering the Sacraments was instituted. For through the Word and Sacraments, as through instruments, the Holy Ghost is given, who works faith; where and when it pleases God, in them that hear the Gospel, to wit, that God, not for our own merits, but for Christ's sake, justifies those who believe that they are received into grace for Christ's sake.
Augsburg Confession V On the Ministry
How would Satan seek to prevent people from coming to saving faith? First, by discrediting the Holy Ministry either by false doctrine or scandalous living among its inhabitants; Second, by casting doubt upon the efficacy of Word and Sacraments to really bring the Holy Spirit when and where it pleases God in them that hear the Gospel. We can see what a deplorable state Christianity falls into when these two strategies succeed to any extent as is the case in the Roman and Evangelical Churches. In the former the ministers of the Gospel are discredited while in the latter the means of grace are despised. We can only cry out with Queen Esther: "Help me, who am alone and have no help but you!"