The phrase “first impressions are lasting impressions” is well known. Hence, when going to the home of one’s prospective in-laws for a proposal or when going for a job interview, a person ensures that he is on his very best behaviour, as he wishes to create a positive impression that will hopefully remain a lasting impression.
Similarly, Islam teaches us that when a child is born, then the very first thing that should be done is to call out the azaan in his right ear and the iqaamah in his left ear. In this manner, the child’s very first impression is the impression of Islam and the greatness of Allah Ta‘ala.
Aside from being a teaching of Islam, this azaan and iqaamah in the ears of the new-born child contains numerous benefits. If the very first words that the child heard, when entering the world, were the words of the kalimah in the azaan, then it is hoped that the final words of the child, when leaving this world, will also be the words of the kalimah. An additional benefit is that of repelling Shaitaan. When the azaan is called out, Shaitaan is forced to flee. Hence, as soon as the child is born, we chase Shaitaan away and ensure that the child hears the invitation to Deen in the form of azaan.
Finally, the name of Allah Ta‘ala and the kalimah are such that they have a definite, positive effect on the person hearing them, even if he does not realize it. Thus, we strengthen the Deen of this new-born child with the kalimah and azaan, just as the doctors attempt to strengthen his immune system with vitamin injections, etc.