Everybody in this world are only HINDUS.I quote this with authority as the first religion was only the vedic within which fold the entire humanity was created.While other religions may not to it,please analyse the following.
1.All religions emanate from a founder which means that religion was not there before the founder.So what religion people were following before that?When mankind was created,God also created a religion for them to attain salvation.Hence any religion which starts from a founder was not before him.
2.Hence the only religion which was there from time immemorial is Hindusim.
3.People who are attracted towards Hinduism and its philosophy,but born in other religions now can follow the samanya dharma prescribed for entire mankind.The vishesha dharma prescribed for others cannot be practised as they have been made by God to be born to non hindu parents which we should not try to alter by converting them as Hindus.It would mean going against the wishes of God