Why is celebrating the Mawlid considered an act of worship, and is every newly invented matter considered a Bid‘ah?

Innovations in religion are reprehensible because they are attributed to religion, unlike permissible worldly innovations such as the invention of the clock and the car. The celebration of the Mawlid (Prophet's birthday) is an innovation in religion through which its practitioners seek to draw closer to Allah, while Allah is not approached except through what He has legislated. Acts of worship are based on divine law, not on innovation, in accordance with His saying, the Almighty: "Then We put you, [O Muhammad], on an [obvious] way of religion; so follow it and do not follow the desires of those who do not know," and His saying: "Or have they partners who ordained for them in religion that which Allah has not authorized?" And as it is authentically reported in Sunan al-Tirmidhi: "Adhere to my Sunnah and the Sunnah of the rightly guided Caliphs; cling to it with your molars. Beware of newly invented matters, for every newly invented matter is a misguided innovation." And in Sahih Muslim: "The best guidance is the guidance of Muhammad (peace be upon him), and the worst of affairs are their newly invented matters, and every innovation is misguidance."

This is not strictness, but rather it is the dictate of the proofs and the sayings of the imams. Indeed, the celebration of the Mawlid was condemned by: Shaykh al-Islam Ibn Taymiyyah, Imam al-Shatibi, Ibn al-Hajj, Shaykh Taj al-Din al-Lakhmi, Shaykh Muhammad Bashir al-Sahsawani, Sayyid Muhammad Rashid Rida, Shaykh Muhammad ibn Ibrahim Al ash-Shaykh, Shaykh Abdul Aziz ibn Baz, and others.

One who celebrates the Mawlid is not considered outside of faith; indeed, these transgressions may occur out of ignorance and good intention, and he must be warned. This is the stance of Ahl al-Sunnah wa al-Jama'ah (the People of the Sunnah and the Community). The motive of those who celebrate is love for the Prophet (peace be upon him), but love necessitates following the Sunnah and conforming to the divine law, in accordance with the poet's saying: "If your love were sincere, you would have obeyed him; for indeed, the lover is obedient to the one he loves."