Aarti means nothing, one can have faith or just go about going through the motions without being "religious". As a non religious person, I did aarti on Diwali, why not, may the gods bless us with prosperity and peace, we were cracking jokes about when god will 'chappar faad' ke give, pls gib some, Mr bhagwan ji !
Its just a cultural thing, and its beautiful, and its been going on for 1000s of years, nobody is forcefully converting muslims if they choose to take part in some random ritual, doesn't make them any less muslim afaic, only the zealot isis minded mullahs have a problem.