undoubting

adj

1. (not-comparable, usually)Experiencing or harboring no doubts; entirely confident.

   “And we shall have an undoubting assurance that that this Kingdom is in such a measure within us, as will ripen to perfection in due time.”

   “And God's declared design in all this is, that the heirs of the promises might have an undoubting hope.”

   “With undoubting decision she directly began her adieus; […]”

   “It was the part of a gentleman to preserve a bearing that was, as far as he could make it, the bearing of an undoubting lover.”

   “This overstuffed, smug, showy and sentimental music can almost persuade when it is performed with undoubting conviction.”