The evidence in the Qur’aan and Sunnah indicates that celebrating birthdays is a kind of bid’ah ( innovation in religion), which has no basis in the pure sharee’ah. It is not permitted to accept invitations to birthday celebrations, because this involves supporting and encouraging bid’ah. Allaah, may He be glorified and exalted, says (interpretation of the meaning):
“Or have they partners with Allaah (false gods) who have instituted for them a religion which Allaah has not allowed…?” [al-Shoora 42:21]
According to saheeh reports, the Prophet (peace and blessings of Allaah be upon him) said: “Whoever does something that is a not part of this matter of ours (i.e. Islam) will have it rejected” (reported by Muslim in his Saheeh ); and “The best of speech is the Book of Allaah and the best of guidance is the guidance of Muhammad (peace and blessings of Allaah be upon him). The most evil of things are those which have been newly invented (in religion), and every innovation is a going astray.”
There are many other ahaadeeth that convey the same meaning.
Besides being bid’ah and having no basis in sharee’ah, these birthday celebrations also involve imitation of the Jews and Christians in their birthday celebrations. The Prophet (peace and blessings of Allaah be upon him) said, warning us against following their ways and traditions: “You would follow the ways of those who came before you step by step, to such an extent that if they were to enter a lizard’s hole, you would enter it too.” They said, “O Messenger of Allaah, (do you mean) the Jews and Christians?” He said, “Who else?” (Reported by al-Bukhaari and Muslim).
The Prophet (peace and blessings of Allaah be upon him) also said: “Whoever imitates a group people is one of them.”
…May Allah give us a better understanding & guide us to accept the truth