How should he deal with his family who celebrate the Prophet’s birthday (Mawlid) and make comments about him because he does not join them?
Question

I do not celebrate the Prophet’s birthday (Mawlid), unlike the rest of my family who do celebrate it, and they say that my Islam is a “new Islam” and that I do not love the Prophet (blessings and peace of Allah be upon him). Can you offer me any advice about that?
Praise be to Allah.Firstly: 
You have done well by not celebrating something that is an innovation (bid‘ah) that has become customary and is widespread among the people, and you should not pay any attention to those who criticise your following the Prophet (blessings and peace of Allah be upon him) and make comments about you because of your adherence to the teachings of Islam. For there is no Messenger whom Allah, may He be exalted, sent to his people but they ridiculed him, and cast aspersions on his soundness of mind and religious commitment, as Allah, may He be exalted, says (interpretation of the meaning): “Likewise, no Messenger came to those before them, but they said: ‘A sorcerer or a madman!’” [adh-Dhaariyaat 51:52]. You have a good example in the Prophets of Allah, so be patient in bearing what you are faced with of annoyance, and seek reward for that with your Lord. 
Secondly: 
Our advice to you is to turn away from debating and arguing with them, unless you see anyone among them who is reasonable and will listen and benefit from it, in which case you can select some of these people to tell them about the reality of the Mawlid, the rulings on it and the evidence for its invalidity, and you can explain to them the virtue of following the (Sunnah of the) Prophet (blessings and peace of Allah be upon him) and the evil of innovation. If you see any such people, there follow some suggestions that may help you in debating with them and advising them: 
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First of all we may start with where they are at, which is that they have told you that your Islam is a “new Islam”. We say: which one is following the older Islam: the one who celebrates the Prophet’s birthday (Mawlid) or the one who does not celebrate it? The answer in the mind of any rational and fair-minded person will undoubtedly be that the one who does not celebrate it is following the older Islam. The Sahaabah (may Allah be pleased with them), the Taabi‘een and their followers, and those who came after them – until the ‘Ubaydi era in Egypt [the ‘Ubaydis followed an extreme form of Shi‘ism] – did not celebrate the Mawlid. Rather that was introduced after their time, so who is it that is following a “new Islam”? 
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We should see who loves the Prophet (blessings and peace of Allah be upon him) more. Is it the Sahaabah (may Allah be pleased with them all) or those who came after them in later centuries?  The answer in the mind of any rational and fair-minded person will undoubtedly be that the Sahaabah loved the Prophet (blessings and peace of Allah be upon him) more. Did they celebrate his birthday or not? So how can these people, by celebrating the birthday of the Prophet (blessings and peace of Allah be upon him), be competing with the noble Sahaabah in love for their Prophet? 
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We should ask: what does it mean to love the Prophet (blessings and peace of Allah be upon him)? In the mind of any rational and fair-minded person, loving him means following his teachings and his path (blessings and peace of Allah be upon him). If these people who celebrate his birthday really followed the teachings of their Prophet and followed his path, they would be content with what the Sahaabah were content with, who loved and followed their Prophet (blessings and peace of Allah be upon him), and they would realise that goodness lies in following those who came earlier and evil lies in the innovations introduced by those who came later. 
Al-Qaadi ‘Iyaad (may Allah have mercy on him) said, in a chapter on the signs of love of the Prophet (blessings and peace of Allah be upon him):
It should be understood that the one who loves a thing gives it precedence and gives precedence to what is in accordance with it, otherwise he is not sincere in his love, and he is a mere pretender. The one who sincerely loves the Prophet (blessings and peace of Allah be upon him) is the one in whom signs of that appear, the first of which is following his example, adhering to his Sunnah, emulating him in word and deed, complying with his commands, avoiding that which he prohibited, and striving to follow his teachings in times of hardship and of ease, when one feels energetic and when one feels reluctant. This is what Allah, may He be exalted, refers to in the verse in which He says (interpretation of the meaning): “Say (O Muhammad (blessings and peace of Allah be upon him) to mankind): ‘If you (really) love Allah then follow me (i.e. accept Islamic Monotheism, follow the Quran and the Sunnah), Allah will love you’” [Aal ‘Imraan 3:31]. So we should give precedence to what he prescribed and encouraged over our own whims and desires. Allah, may He be exalted, says (blessings and peace of Allah be upon him): “And those who, before them, had homes (in Al-Madinah) and had adopted the Faith, love those who emigrate to them, and have no jealousy in their hearts for that which they have been given (from the booty of Banu An-Nadeer), and give them (emigrants) preference over themselves, even though they were in need of that” [al-Hashr 59:9]. And another sign of love is that one should be prepared to anger people for the sake of pleasing Allah. 
The one who has this characteristic has attained perfect love for Allah and His Messenger; the one who goes against that in some of these ways has fallen short in his love, although he has not failed completely. 
Ash-Shifa bi Ta‘reef Huqooq al-Mustafa (2/24-25) 
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We should look and see whether anything is proven about the date of the birth of the Prophet (blessings and peace of Allah be upon him). Then, on the other hand, we should look and see whether anything is proven about the date of his death (blessings and peace of Allah be upon him). The answer for any rational and fair-minded person is that the date of his birth is not proven, although the date of his death has been proven with certainty. 
If we look at the books of Seerah (Prophet’s biography), we will find that the writers of the Seerah differed concerning the date of the Prophet’s birth, and there are several opinions, as follows: 
1.Monday 2nd Rabee‘ al-Awwal
2.8th Rabee‘ al-Awwal
3.10th Rabee‘ al-Awwal
4.12th Rabee‘ al-Awwal
5.Az-Zubayr ibn Bakkaar said: He was born in Ramadan.
If any issue was connected to the date of his birth (blessings and peace of Allah be upon him), the Sahaabah (may Allah be pleased with him) would have asked him about that or he himself (blessings and peace of Allah be upon him) would have told them about it, but no such thing happened. 
With regard to his death, there was no difference of opinion concerning the fact that it occurred on 12th Rabee‘ al-Awwal 11 AH. 
Then after that we should look at when these innovators celebrate: they celebrate on the date of his death, not his birth! The baatini (esoteric) ‘Ubaydis – who fabricated their lineage and called themselves the Faatimis (Fatimids) after Faatimah (may Allah be pleased with her) – convinced the people of their bid‘ah and the people foolishly accepted it. Those people were heretics who wanted to express joy on the occasion of the death of our Prophet Muhammad (blessings and peace of Allah be upon him), so they invented this occasion and held celebrations at that time. Their aim was to express their joy, but the simple-minded among the Muslims thought that those who went along with them in those celebrations were only expressing their love for the Prophet (blessings and peace of Allah be upon him). Thus their evil plot succeeded and they also succeeded in distorting the meaning of love and turned it into the reciting of qaseedahs for the Mawlid and distributing barley and sweets, and holding parties in which there is dancing and mixing between men and women, accompanied by music, wanton display and immoral actions, in addition to these innovated kinds of supplication and words of shirk that are spoken in those gatherings and circles. 
On our website we have previously explained in detail what is wrong with this innovation. Please see the answers to questions no. 10070, 13810 and 70317 
Please see also the book by Shaykh Saalih al-Fawzaan criticising this innovation, which is entitled Hukm al-Ihtifaal bi’l-Mawlid an-Nabawi. 
Thirdly: 
Be patient and steadfast in following your Prophet Muhammad (blessings and peace of Allah be upon him) and do not be deceived by the large numbers of those who go against it. We advise you to seek knowledge and be keen to benefit people, and do not let these actions on the part of your family be a cause of separation between you and them. For they are only imitating others who have given them fatwas stating that these parties are permissible or even mustahabb (encouraged). So you have to deal with them kindly when objecting to it, and strive to show them the best words, deeds and attitude. Show them the effect of following the Sunnah on your conduct and worship. We ask Allah to guide you and give you strength. 
And Allah knows best.