Let us consider a unique case. In Matthew 24, Jesus is instructing His disciples about what they should do when the Roman army came to destroy Jerusalem.  Jesus was able to foresee, and forewarn His disciples about a forth-coming battle that would totally demolish the city.  He gave them certain signs to look for so they would know the time was near. He wanted them to flee from the city to the hills when that army came.  And in preparation for that event He said, ‘Pray that your flight may not be in winter or on the Sabbath" (Matt. 24:20).

On the Sabbath, the gates of the city would be closed and they could not get away.  In the winter, travel would be difficult at best.  So He told them to pray that their flight would not be at those times.  But notice: their flight would be when the army came. 

That is equivalent to praying for the army to come (or not come) at a certain time.  Imagine that!  The prayers of the Christians determining the time the heathen army would arrive in Jerusalem.

Prayer is powerful.  It can even determine the course of a heathen army!  That means the prayers of the saints were more powerful than Caesar!  Yes, prayer avails.  Else Jesus taught His disciples to pray in vain.

We may not always understand how God hears,

nor why He answers us the way He does, but this we know:

He is our Father and we can talk to Him!