السلام عليكم ورحمة الله وبركاته
i dont mean to be strict, But the evidence in the Qur’aan and Sunnah indicates that celebrating birthdays is a kind of bid’ah or 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.
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)
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).
Speaking about the same issue Sheikh Faysal Mawlawi, Deputy Chairman of the European Council for Fatwa and Research, adds:
“Permissibility is the original ruling in this case, as there is no evidence of prohibition. The principle of not following the Jews and Christians is really required in matters of their false claims and beliefs in relation to religion. Such beliefs are no more than disbelief from an Islamic perspective.
In this context, people must be aware that celebrating such occasions, e.g. the Prophet’s birthday, is no more than a matter of habit, and by no means a religious requirement. However, if it entails any forbidden practices, such a celebration becomes forbidden for that reason alone. Moreover, a celebration of this sort becomes recommended if it includes recommended acts of worship.
May Allah grant you all long life full of good deeds and woshiping.
for more:
http://www.islamicacademy.org/html/Articles/English/BID'AH - Innovation in Islam.htm