Such innovators were the Mu'tazilites, Qadarites, Murji'ites etc. Their innovations were harmful to the Deen and were devoid of benefit. As to actions, they must be viewed in the light of the Blessed Nabi's Sunnah, or way of judging, and accepting or rejecting. The classifications of Izz ibn Abd as Salam has been a handy aid for Islamic scholars in determining the value of any new act. Much more can be said on this subject but it is beyond the present scope of this work.
Salaams are upon the anbiyya on the days of their birth.
In these ayats, Allah Ta'ala makes clear that the birthdays of nabis, alaihim salaam, are special, marked by the peace that Allah Ta'ala sends down upon them at that time. Although the Holy Qur'an only mentions Hadrat Isa and Hadrat Yahya as having Salaam upon them the day they were born, the obvious inference is that Salaam is upon all the anbiyya the day they were born. That the times when Allah Ta'ala's Salaam being sent down is a special time is indicated in the Sura al Qadr . Thus, the time of the birth of a nabi is special by reason of the Salaam of Allah being sent down. An unbeliever receives Mercy from Allah because he celebrated the Mawlid of the Holy Last Messenger, sallallahu alaihi wa sallam .