(From the Heidelberg Catechism, 1563)
Question 129. What does the word “Amen” signify?
Answer: “Amen” signifies, it shall truly and certainly be: for my prayer is more assuredly heard of God, than I feel in my heart that I desire these things of him. ( 2 Cor.1:20 For all the promises of God in him are yea, and in him Amen, unto the glory of God by us. 2 Tim.2:13 If we believe not, yet he abideth faithful: he cannot deny himself.)
Barth says, “In Question 129 of the Heidelberg Catechism it is stated that the answer to our prayer is more certain than our awareness of the things that we request” (Barth, Prayer Westminster/John Knox Press, 2002.)