How can a recently converted Muslim girl, who fears displeasing her Christian parents, declare her Islam, change her ID card, and leave the family home to move to another province without informing them, and is this permissible in Sharia?

Islam becomes valid simply by uttering the two testimonies of faith (Shahadatayn) with belief in their meaning and commitment to their implications. It is not a condition to publicize one's conversion, but it is preferable to declare it and invite others to it if no harm is feared. One must be keen to invite parents and relatives to Islam with wisdom and good admonition, following the example of Ibrahim (peace be upon him) in his call to his father, and striving to bring them closer to Islam. It is advisable to seek assistance from official institutions and non-governmental organizations to complete the formal procedures for declaring one's conversion to Islam.