Islam means submission to Allah (SWT) with Tauhid.
* Testimony of Faith [There is None worthy of worship except Allah (SWT) and Muhammad (SAW) is the final Messenger of Allah (SWT)]
* To establish Salat (prayers).
* To pay Zakat (poor tax).
* To observe Saum (fasting) in the month of Ramadan.
* Hajj [(pilgrimage to the Sacred House (Kabah) in Mecca (Saudia Arabia)] once in your lifetime, if one can afford the journey.
What are the nullifiers of Islam?
The nullifiers of Islam are ten:
1. Polytheism of worship.
2. He/she who does not believe that the polytheists are disbelievers, or doubts their infidelity or holds their belief to be valid.
3. He/she who sets up intermediaries between one's self and Allah (SWT) supplicating them, trusting them and asking them to intercede on his behalf.
4. He/she who believes that the guidance of others is more perfect than the guidance of Prophet Muhammad (SAW).
5. He/she who hates anything that Prophet Muhammad (SAW) was sent with.
6. He/she who denies the religion of Prophet Muhammad (SAW) or ridicules it's reward or punishment.
7. Sorcery.
8. Supporting the polytheists against the Muslims
9. He who believes that some people are exempted from abiding by the Shariah (Islamic Law) as Khidr (AS) was exempted by the laws of Musa (AS).
10. Turning away from the religion of Allah (SWT) by neither learning nor applying it.