Can Allah forgive a sister who was Muslim by birth but converted to Christianity due to being raised in a Christian environment and her father's neglect?

Whoever dies upon a religion other than Islam, after having learned of the message of Prophet Muhammad (peace be upon him), will abide eternally in Hellfire, as Allah Almighty says: "And whoever of the [various] parties disbelieves in him - then Hellfire is his promised abode" (Quran 11:17), and His saying: "And whoever desires a religion other than Islam, it will never be accepted from him, and in the Hereafter he will be among the losers" (Quran 3:85). It is also mentioned in the prophetic Hadith that whoever among the Jews or Christians hears of the Messenger and does not believe in him, he will be among the inhabitants of the Fire. The duty is to invite her to Islam, and the father should try to take her to raise her among Muslims, perhaps she will be drawn to Islam.