The first Pillar of Islam is Shahadah. This is a declaration of faith, a bit like a Muslim creed. The words are spoken throughout the day, particularly at prayer times, and also at important times of life, especially at birth and death.
“La ilaha illa Allah Muhammad Rasulu Allah”
“There is no God but Allah; Muhammad is Allah’s messenger.”
The Shahadah emphasises the oneness of God (Arabic- Tawhid) and denies that there is anything else worth worshipping. The second part emphasises that Muhammad (SAW) was the ONLY the messenger of Allah, and He did not need worshipping. He was very important. Muslims should not pray or worship Muhammad (SAW).
Muslims reject polytheism (worship of many gods) and Trinitarianism (Christian belief that god is three-in-one).
Shahadah is the most important of the Five Pillars of Islam. If you do not say the Shahadah you are not considered as a Muslim.