Sarah was 90 years old when she was told she would give birth to a son. Zechariah was well passed the age when a normal person becomes a father when he was promised a child. Both had spent years praying, longing, hoping, and grieving over the desire for children. So you can imagine their amazement (and shock) when they are told that they will soon receive the desire of their heart. But their reaction is more than just shock. It's unbelief (Genesis 18; Luke 1). And they were rebuked for their mistrust of what God said he would do. Years and years of waiting made good news seem impossible. They probably had given up hope that children would ever be a reality for them. They were so used to bad news, that when good news came it didn't seem real.
I don't blame them. I, too, have wrestled with this same unbelief in recent months. Whenever God provides for us and answers a prayer I have doubted that he is really working in my life. I have assumed his answer of infertility means a lack of care, and therefore any other answer to our needs and desires is not really evidence of love and care for me, his child. I've prepared myself for bad news for so long that when good news comes I have a hard time seeing it as good. One of the glorious things about the Bible is that it reveals the human heart in fresh ways. My sinfulness is laid bare when I am exposed to God's word, and I'm not alone. The tendency to doubt God's goodness has been a thorn in our flesh since Adam fell in the Garden. And it still causes problems today.
Sarah's laughter, Zechariah's questions, and my doubting all reveal the same thing: a heart that doesn't trust God. Sarah and Zechariah were rebuked because they didn't trust God. Their initial reaction to God's promises for them revealed that they doubted his good plan for them. My reaction to answered prayer does the same.
These reactions are the opposite of faith. Faith is believing what you cannot see. I didn't see Jesus die for my sins, but I have faith that what God says is true and what he completed on the cross is sufficient for my sins. Doubt is believing what you can see. Another negative pregnancy test feels like, and looks like (at first glance), God has forgotten me.
The reason I (and every other biblical character who doubted) have a hard time with good news is because I've gotten into a pattern of doubting God's good plan for my life. So when his good plan includes a favorable answer to my prayers (even if it is small), I can't see it for what it is. I doubt that it is real. I doubt that he can do all things. I doubt that he is truly working in my situation.
Thankfully sanctified faith is not a prerequesite for answer to my prayers. Like Sarah and Zechariah, I need some chastening and help from the Holy Spirit when I am tempted (and give in) to doubt God's good purposes.
God is in the business of answering our prayers and giving us eyes to see his great love and care for us. Sometimes he lets us see a small glimpse of what he is doing in our lives. Other times he covers his purpose with a veil so we learn to trust him more in the darkness. Even when we can't see behind the veil, he is still working, answering prayers, increasing our faith, and preparing us for glory.