Some good words from Pastor Luther

From Luther on "Living and Dying as a Christian". (Lull, p. 648, 649;  written in 1519)

Sixteenth, it is of utmost importance that we highly esteem, honor, and rely upon the holy sacraments, which contain nothing but God's words, promises, and signs.  This means that we have no doubts about the sacraments or the things of which they are certain signs, for if we doubt these we lose everything.  Christ says that it will happen to us as we believe.  What will it profit you to assume and to believe that sin, death, and hell are overcome in Christ for others, but not to believe that your sin, your death, and your hell are also vanquished and wiped out and that you are thus redeemed?  Under those circumstances the sacraments will be completely fruitless, since you do not believe the things which are indicated, given, and promised there to you.  That is the vilest sin that can be committed, for God himself is looked upon as a liar in his Word, signs, and works, as one who speaks, shows, and promises something which he neither means nor intends to keep.    Therefore we dare not trifle with the sacraments.  Faith must be present for a firm reliance and cheerful venturing on such signs and promises of God. What sort of a God or Savior would he be who could not or would not save us from sin, death, and hell?  Whatever the true God promises and effects must be something big.

But then the devil comes along and whispers into your ear, "But suppose you received the sacraments unworthily and through your unworthiness robbed yourself of such grace?" In that event cross yourself and do not let the question of your worthiness or unworthiness assail you.  Just see to it that you believe that these are sure signs, true words of God, and then you will indeed be and remain worthy.  Belief makes you worthy;  unbelief makes you unworthy.  The evil spirit brings up the question of worthiness and unworthiness to stir up doubts within you, thus nullifying the sacraments with their benefits and making God a liar in what he says.

God give you nothing because of your worthiness, nor does he build his Word and sacraments on your worthiness, but out of sheer grace he establishes you, unworthy one, on the foundation of his Word and signs.  Hold fast to that and say, "He who gives and has given me his signs and his Word, which assure me that Christ's life, grace, and heaven have kept my sin, death, and hell from harming me, is truly God, who will surely preserve these things for me.  When the priest absolves me, I trust in this as in God's Word itself.  since it is god's Word, it must come true.  That is my stand, and on that stand I will die."  You must trust in the priest's absolution as firmly as though god had sent a special angel or apostle to you, yes, as though Christ himself were absolving you.

Seventeenth, we must note that he who receives the sacraments has a great advantage  for he has received a sign and a promise from God with which he can exercise and strengthen his belief that he has been called into Christ's image and to his benefits.  The others who must do without these signs labor solely in faith and must obtain theses benefits with the desires of their hearts.  They will, of course, also receive these benefits if they persevere in that same faith.