In Luke 1 v18-25 Zechariah struggles to believe that he will father John the Baptist in his old age. Despite his disbelief, God graciously fulfils His word and blesses Zechariah and his wife Elizabeth with a child as part of His salvation plan.

Luke 1:18–25

18 And Zechariah said to the angel, “How shall I know this? For I am an old man, and my wife is advanced in years.” 19 And the angel answered him, “I am Gabriel. I stand in the presence of God, and I was sent to speak to you and to bring you this good news. 20 And behold, you will be silent and unable to speak until the day that these things take place, because you did not believe my words, which will be fulfilled in their time.” 21 And the people were waiting for Zechariah, and they were wondering at his delay in the temple. 22 And when he came out, he was unable to speak to them, and they realized that he had seen a vision in the temple. And he kept making signs to them and remained mute. 23 And when his time of service was ended, he went to his home.

24 After these days his wife Elizabeth conceived, and for five months she kept herself hidden, saying, 25 “Thus the Lord has done for me in the days when he looked on me, to take away my reproach among people.”

(ESV)