The unnatural mind knows not Isaiah 9: 6 - 7 never fulfilled, thinks it has been

Words are the only source by which situation is identified.  But in the case of the blind believing ones, they can't tell when things are fulfill from when it's not. In the case that the bible prophecy said, Jesus boy child was to be born, at a time appointed by the Spirit-God. The indicated time came and went, now at a distance of 2018 years, and there is no apparent sign of the fulfillment. What should believers do in this case. Pretend like it happened, or declare it a false prophecy. What is the correct procedure that should go into effect to resolve  such an issue.