In Islam, the purpose of life is "ibadah", or, to worship the One True Almighty God on His terms and His conditions. Total and complete submission to the will of Allah is the only purpose. Everything else should flow from that. As you can see, Islam is not all together different than Christianity and Judaism.
The purpose of life in Islam (aside from my ideas on it) is spelled out in the five pillars of Islam. I won't go in depth, as I am lazy. Here's a link,
I am a link.
1) I testify that there is no god (ilah) but Allah, and I testify that Muhammad is the messenger of Allah.
2) The second pillar of Islam is Salah, the requirement to pray five times a day at fixed times.
3) Zakah, or alms-giving, is the practice of charitable giving by Muslims based on accumulated wealth, and is obligatory for all who are able to do so.
4) Ritual fasting is an obligatory act during the month of Ramadan.
5) The Hajj is a pilgrimage that occurs during the Islamic month of Dhu al-Hijjah in the city of Mecca.
The story of Islam as told from the point of view of a cynic.
Once upon a time there was much turmoil in what would become the middle east. A trader by the name of Muhammad was having a hard go of it due to the constant fighting. One day he rode a winged stallion to mecca and shot up to heaven via the rock to talk with god. God told him "stuff" and that "stuff" was that the people of the region should stop fighting and concentrate on getting to mecca, which just so happened to be a central trading point. God hastened to add that people should give 1/5? of their income to the new religion for reasons not really defined.
This has been Islam in 30 seconds or less with an ex-army cynic. Sadly, all of this is from memory of a briefing on Islam.