The first of the Five Pillars of Islam is the Declaration or Testimony of Faith (called Shahada in Arabic), to which every Muslim must adhere. The word Shahada in Arabic linguistically translates to 'testifying, bearing witness.' The Shahada is the Islamic creed. The Shahada contains two parts, both of which a Muslim must testify to and believe.
The first part requires the believer to testify that no deity is worthy of worship, veneration, or complete devotion, other than Allah. A Muslim acknowledges that Allah has the exclusive right to be worshipped, venerated, loved, inwardly and outwardly, by one's heart, tongue, and limbs. A Muslim accepts Allah as the only God, Master, Lord, and Ruler. Allah is not a foreign God, as Allah is the Arabic name for God. Islam states that God has none partners or associates in worship. No other deity, being, or idol is worthy of worship. The act of worshipping any other besides Allah is the biggest sin in Islam; standing as the only sin that is not forgiven if a person dies in that state without repenting.
Regretfully, many have regarded certain historical figures as their gods and deities, who are wrongfully worshipped and venerated; whether they are idols, superstitions, saints, ideologies, ways of life, or any authority figures who claim to be divine or semi-divine--even though they themselves are creations and have no power to bring any benefit or harm to anyone.
"But they have taken besides Him gods which create nothing, while they are created, and possess not for themselves any harm or benefit and possess not [power to cause] death or life or resurrection" (Quran 25:3)
The belief in worshipping the One God is considered the central Message of all of God's Prophets and Messengers, who were sent to humanity to deliver His Message. This was the Message of Prophet Adam, Prophet Noah, Prophet Abraham, Prophet Moses, Prophet Jesus, and Prophet Muhamad; peace be upon them all.
"And We certainly sent into every nation a messenger, [saying], ‘Worship Allah and avoid false deities..." (Quran 16:36)
Through verbally stating these words, believing in them, acting and living upon them, one enters the fold of Islam. Merely saying these words verbally without action does not complete a Muslim.
The second part of the testimony requires the believer to testify that Prophet Muhammad is the Messenger of God. In accepting Prophet Muhammad as the 'seal of the Prophets,' one affirms the belief that his Prophecy confirms and fulfills all the previously revealed Messages beginning with Prophet Adam. Peace be upon him. Whereas Muslims believe in all the previous Messengers and Prophets of God, Islam states Prophet Muhamad is both a Messenger and Prophet of God; one who carries a higher role than all previous Messengers and Prophets before him. Prophet Muhammad was a mere mortal with no share in Divinity, who was chosen by God the Almighty, as the last and final Prophet to the last nation, our nation.
"Muhammad is not the father of [any] one of your men, but [he is] the Messenger of Allah and last of the prophets. And ever is Allah, of all things, Knowing" (Quran 33:40)
A Muslim is required to fully carry out in practice the instruction given by Prophet Muhammad, as commanded by God the Almighty. Prophet Muhammad also serves as the best role model for mankind that ever-stepped foot on Earth, by his exemplary life. Muslims are encouraged to attempt to follow and emulate Prophet Muhammad's examples, manners, generosity, good habits, politeness, respect, gentleness, noble feelings, and way of life to the best of their ability, reflecting an emphasis on Islam and the Holy Quran.
"There has certainly been for you in the Messenger of Allah an excellent pattern for anyone whose hope is in Allah and the Last Day and [who] remembers Allah often" (Quran 33:21)
These two phrases are the most frequently repeated words in the world, as hundreds of millions of practicing Muslims repeat these words dozens of times throughout their day and through their prayers. It is recommended for a believer to say it when they first rise in the morning and before going to bed. These words reflect and encompass every dimension of a Muslim's life.
The Shahada (testimony of faith) is by far the essential aspect of Islam, as it affirms the belief in the Oneness and Uniqueness of Allah, upon which the whole Religion of Islam is built upon, and all other beliefs hinge. It is the central belief that a Muslim adheres to his entire life. Verbally stating these words and living by them is unquestionably the most significant and most important duty of a Muslim. Unless one acknowledges this testimony, he or she cannot be a Muslim.
Muslims strain to utter these words as their last spoken before departing this world since whoever does so has been promised the destiny of God-given Paradise. However, only the ones that lived and acted upon these words will be granted the ability to utter these blessed sentiments in the form of their final words.