Belief In Other Scriptures
This belief is not a belief in their current form, rather a belief that they indeed were revealed by God at whatever time they were revealed. Implication being, they are all from the one God, the only creator of this universe, as explained by Ghamidi Sahab as well. To study them as a Muslim, we have to do that under umbrella of Quran. وَأَنزَلْنَا إِلَيْكَ الْكِتَابَ بِالْحَقِّ مُصَدِّقًا لِّمَا بَيْنَ يَدَيْهِ مِنَ الْكِتَابِ وَمُهَيْمِنًا عَلَيْهِ فَاحْكُم بَيْنَهُم بِمَا أَنزَلَ اللّهُ وَلاَ تَتَّبِعْ أَهْوَاءهُمْ عَمَّا جَاءكَ مِنَ الْحَقِّ (٥: ٤٨) And [O Prophet!] We have revealed to you the Book with the truth in confirmation of the Book before it, and standing as a guardian over it. Therefore, give judgement among men according to the guidance revealed by God and do not yield to their whims by swerving from the truth revealed to you . (5:48)