wr wb
....i took this topic from a islamic web so may u get clear with this point of ur birthright in islam..read more please....

Islam states clearly that everyone is born a Muslim and is therefore monotheistic by nature. We read in the Qur'an that humanity has been created with the natural disposition towards the unity of God. This is to be expected, for Allah, who has breathed His spirit into each of us, is Himself the example of perfect unity. In the words of the Prophet Muhammad: "Every person is born with the innate religious faith (to submit to God Almighty)." Thus when an individual accepts Islam, he is not turning his back on any prior revelation but rather is returning to the original and true revelation of Allah and to his own nature as a creation of Allah. This being the case, Islam is your birthright-other religious or ideological systems are either corruptions our outright denials of Islam.
http://www.sultan.org/