A British boy is asking why the Prophet (peace and blessings of Allaah be upon him) chose the five pillars
Question

                Why did Muhammed choose the five pillars ?
Praise be to Allah.This 
          question caught our attention, because it indicates that you have an 
          interest in the religion of Islam and in the Prophet of Islam. We congratulate 
          you for this interest and your keenness to find out about these things 
          from trustworthy sources.  Perhaps this question will open the 
          way for you to reach the path of truth, for Allaah is the Guide to the 
          Straight Path. Here is the answer :  
Muhammad 
          
          (peace and blessings of Allaah be upon him) is the Prophet whom Allaah 
          sent to all of mankind, to bring them forth from the darkness of polytheism 
          and disbelief to the light of guidance and Islam. Allaah commanded him 
          to call people to worship Allaah alone, with no partner or associate, 
          and to enjoin good characteristics upon them, such as generosity, courage, 
          honouring one’s guest, treating neighbours kindly, obeying one’s parents, 
          respecting the old and being compassionate towards the young, guiding 
          those who are misguided, showing mercy to the poor and needy, helping 
          those who are in need, helping those who are troubled, relieving those 
          who are in distress, and other kinds of good characteristics… and to 
          forbid polytheism, disbelief and evil characteristics and actions such 
          as adultery, lying, treachery, deceit, disobedience to parents, wrongdoing, 
          etc. See question # 219. 
 With 
          regard to the pillars of Islam, it should be noted – may Allaah guide 
          you – that the Messenger 
          
          (peace and blessings of Allaah be upon him) was commanded to convey 
          that which Allaah revealed to him, without adding anything or taking 
          anything away. Allaah says (interpretation of the meaning): 
“It is only a Revelation revealed”
[al-Najm 
          53:4].  
It 
          is impossible for the Messenger 
          
          (peace and blessings of Allaah be upon him) to tell lies about Allaah. 
          Allaah says (interpretation of the meaning):  
“And 
          if he (Muhammad) had forged a false saying concerning Us (Allaah), 
We 
          surely would have seized him by his right hand (or with power and might), 
          
And 
          then We certainly would have cut off his life artery (aorta), 
And 
          none of you could have withheld Us from (punishing) him” 
[al-Haaqqah 
          :44-47]  
If 
          we examine the five pillars of Islam, we will see that they vary. The 
          first pillar – the Shahaadatayn or twin testimony of faith – 
          combines action of the heart (belief) with action of the tongue (words). 
          The second pillar – prayer – means doing a physical action which connects 
          a person to his Lord at various times of the night and day. The third 
          pillar, fasting, is an act of worship which involves refraining from 
          food, drink, intercourse and all actions that break the fast, from dawn 
          till sunset. So the Muslim fasts to worship Allaah, and also to feel 
          how his poor brothers feel. The fourth pillar is zakaah, which is a 
          financial action, whereby the Muslim who is able to do so gives part 
          of his wealth to his poor and needy brothers. The fifth pillar is Hajj 
          (pilgrimage), which is an action that combines spending money and physical 
          effort. If you think about these five pillars, you will see great wisdom 
          behind them. Islam is based on submission to Allaah alone, and giving 
          up associating anything or anyone else with Him. It also teaches that 
          Allaah should not be worshipped in any way other than the ways that 
          He has prescribed. There are some people for whom it is easy to do physical 
          actions but it is hard for them to spend money, so zakaah is a test 
          for such people. Some people find it easy to spend a lot of money but 
          it is difficult for them to make physical efforts,  so prayer is 
          a test for them. Some people find it easy to pray and pay zakaah, but 
          it is hard for them to give up the food, drink and physical pleasures 
          that they enjoy, so fasting is a test for them. And Hajj may combine 
          spending money with physical effort… and other praiseworthy reasons 
          behind these acts of worship. 
 These 
          pillars were revealed from Allaah, and conveyed to us by the trustworthy 
          Prophet 
          
          (peace and blessings of Allaah be upon him). The Muslims accept them 
          and carry them out. We ask Allaah to guide us all.