Moving mountains or seedtime and harvest?

While the earth remains, seedtime and harvest, cold and heat, summer and winter, day and night, shall not cease (Gen 8:22; cf. 9:8-17). 

13 Whatever you ask in my name, this I will do, that the Father may be glorified in the Son. 14 If you ask me anything in my name, I will do it (Jn 14:13-14).

He said to them, “Because of your little faith. For truly, I say to you, if you have faith like a grain of mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move, and nothing will be impossible for you.” (Mt 17:20). 

If you believe, you will receive whatever you ask for in prayer (Mt 21:22).

Unanswered prayer is one reason some professing Christians lose their faith. And sometimes the catalyst is more specific than answered prayer. Rather, it's belief that God broke his promise. 

There is, however, a certain tension between prayer and providence. Between prayer promises and the Noahic covenant (Gen 9:8-17; 8:22). In principle, here are different ways to interrelate these promises:

i) Both prayer promises and the uniformity of nature are unconditional. But that's contradictory.

ii) Prayer promises abrogate the Noahaic covenant.

iii) Prayer promises and ordinary providence condition each other.

According to (iii), prayer promises are implicitly conditional. Promises regarding prayer and ordinary providence are relative rather than absolute. They qualify each other. If, on the one hand, God always answers prayer, including nature miracles, that nullifies ordinary providence. If, on the other hand, ordinary providence is ironclad, that nullifies prayer promises. 

Prayer promises need to be understood against the backdrop of the Noahic covenant. The scope of that promise is conveyed through a series of merisms, to express universality. 

We have two kinds of potentially conflicting divine promises: answered prayer and ordinary providence. Both can't be true all the time. For certain prayers require God to circumvent the ordinary course of nature. Prayer promises are only false if they were meant to automatically override ordinary providence. That only follows if Jesus intended to abrogate the Noahic covenant. And that would lead to an utterly chaotic world. Jesus often makes hyperbolic statements. 

The upshot is that these two kinds of divine promises counterbalance each other. We can't predict which takes precedence in any particular case. We find out when we pray. Sometimes prayer overrides providence; conversely, sometimes providence overrides prayer. Which is which is not something we know in advance. Rather, that's something we discover through prayer.