1- There is no need to say "a hindu singer mohit chuhan". He has sung sufi songs as well and there we dont say that a Hindu singer Mohit Chauhan sang that song.
2- The lyrics were written by Sayeed Qadri or Sanjay Masoom. It is not clear however we can say that at least a Muslim was part of the lyricist team of this album and could have pointed it out when album was prepared.
3- Kalma is dervied from kalam which means speech. Similarly deen does not mean Islam only as for a hindu, hinduism is the deen and imaan just means belief. Jannat is not a concept specific to Islam. So literally one can make a case that there was not a reference to Islam.
However the use of word Azaan means that there was probably a reference to Islam.
4- In poetry when one says she is my kalma or deen then most of the time it is figurative and not literal, reflecting importance. In chaiyyan chaiyyan line was "mera naghma tu, mera kalma tu". This did not mean it was religious kalma. What it meant that she holds the importance for me as Kalma is important to a Muslim.
4- This is a movie and it shows a character singing this. The name of the character was Sonu Dill aka KKC i.e. kutti kameene cheez. Basically the girl in question can be his kalma or she can be his deen. It has nothing to do with Muslims though the religon was involved figuratively.
5- The question of shirk does not arise as Mr. KKC is not a Muslim. If you meant shirk in larger context then we know that anyway so this song does not anything new.
6- We are still free to not hear it, watch it etc.
7- I do get your concern as deen, kalma, azaan hold a different meaning for Muslims. Ideally we should avoid these things as to me its needless. There are other words which can show intense emotions for someone. Poets often cross these lines and we see examples of that in Urdu poetry as well. However considering all of the above least we can do is not make it a religious issue.
8- I can't read anyone's heart but my educated guess would be that at worst we should blame the lyricist for being careless
The writer of this post is Muslim also.
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