Assalamu'Alaykum
Subhanallah.
If we just take the time to do some research and look into the history for half the holidays that Muslims now celebrate we would in great shock.
The history of "Birthdays" is one that is rather scary, it was invented by the "PAGANS". For fear of the evil spirts so the families of that person would gather around to protect them since it was a common belief that the evil spirts were more dangerous to a person when he/she experience a change in thier life, such as turing a year older. Thus as a result birthdays was an occasion where family and friends of that individual would surround that person with "laughter and joy" in order to protect them from the "EVIL" instead of gifts most guests brought happy wishes however if they brought presents it was to be considered as good omens.
The custom of lighting candles originated with ppl believing that the "gods" lived in the sky and by lighting candles and torches it was a way for them to send signals or prayers to the "gods" so that they could be answered. Hence blowing out candles and making a whish this was thought of another way of sending the "signals/message" to the "gods". In the ancient times ppl prayed to the flames of an open fire, these were also the same ppl that we know of as being " Fire Worshipers". They believed that the smoke carried their thoughts up to the "gods".
Wa na3oothobillah.
So many Muslims now days in Muslim lands celebrate birthdays out of ignorance.
For us [Muslims] are the two Eids that replace all hoildays,
Hadith - Abu Dawood #1134, 1/675, Narrated Anas Bin Malik
The Prophet came to Medina with two days they played in. The Prophet said, ‘What are these two days?’ They said, ‘These are two days we used to play in, in our Jahiliyah.’ The Prophet said, ‘Allah has replaced them with two better days: Eid Al Adhaa and Eid Al-Fitr’.
In conclusion: We are told to oppose Jews and Christians by doing the opposite of what they do, so now imagine "Birthdays" the custom of the PAGANS shouldnt we then oppose even more so?