1. The Books of Moses, Psalms, and Gospels are all authoritative

2. They have not been corrupted

3. John 1:1,14 says Jesus is God and Genesis 19:24 outlines the Trinity

4. Therefore, if the Quran is true -> the Gospel is true. If the Gospel is true -> Islam is false.

قُولُوا آمَنَّا بِاللَّهِ وَمَا أُنْزِلَ إِلَيْنَا وَمَا أُنْزِلَ إِلَىٰ إِبْرَاهِيمَ وَإِسْمَاعِيلَ وَإِسْحَاقَ وَيَعْقُوبَ وَالْأَسْبَاطِ وَمَا أُوتِيَ مُوسَىٰ وَعِيسَىٰ وَمَا أُوتِيَ النَّبِيُّونَ مِنْ رَبِّهِمْ لَا نُفَرِّقُ بَيْنَ أَحَدٍ مِنْهُمْ وَنَحْنُ لَهُ مُسْلِمُونَ

Say, ˹O believers,˺ “We believe in Allah and what has been revealed to us; and what was revealed to Abraham, Ishmael, Isaac, Jacob, and his descendants; and what was given to Moses, Jesus, and other prophets from their Lord. We make no distinction between any of them, and to Him we have submitted."

۞ إِنَّا أَوْحَيْنَا إِلَيْكَ كَمَا أَوْحَيْنَا إِلَىٰ نُوحٍ وَالنَّبِيِّينَ مِنْ بَعْدِهِ ۚ وَأَوْحَيْنَا إِلَىٰ إِبْرَاهِيمَ وَإِسْمَاعِيلَ وَإِسْحَاقَ وَيَعْقُوبَ وَالْأَسْبَاطِ وَعِيسَىٰ وَأَيُّوبَ وَيُونُسَ وَهَارُونَ وَسُلَيْمَانَ ۚ وَآتَيْنَا دَاوُودَ زَبُورًا

Verily, We have sent the revelation to you (O Muhammad صلى الله عليه وسلم)1 as We sent the revelation to Nûh (Noah) and the Prophets after him; We (also) sent the revelation to Ibrâhîm (Abraham), Ismâ‘îl (Ishmael), Ishâq (Isaac), Ya‘qûb (Jacob), and Al-Asbât [the offspring of the twelve sons of Ya‘qûb (Jacob)], ‘Îsâ (Jesus), Ayyûb (Job), Yûnus (Jonah), Hârûn (Aaron), and Sulaimân (Solomon); and to Dawud [David] We gave the Zabur [Psalms].

إِنَّا أَنْزَلْنَا التَّوْرَاةَ فِيهَا هُدًى وَنُورٌ ۚ يَحْكُمُ بِهَا النَّبِيُّونَ الَّذِينَ أَسْلَمُوا لِلَّذِينَ هَادُوا وَالرَّبَّانِيُّونَ وَالْأَحْبَارُ بِمَا اسْتُحْفِظُوا مِنْ كِتَابِ اللَّهِ وَكَانُوا عَلَيْهِ شُهَدَاءَ ۚ فَلَا تَخْشَوُا النَّاسَ وَاخْشَوْنِ وَلَا تَشْتَرُوا بِآيَاتِي ثَمَنًا قَلِيلًا ۚ وَمَنْ لَمْ يَحْكُمْ بِمَا أَنْزَلَ اللَّهُ فَأُولَٰئِكَ هُمُ الْكَافِرُونَ

Verily, We did send down the Taurat [Books of Moses], therein was guidance and light, by which the Prophets, who submitted themselves to Allah's Will, judged the Jews... and to Musa [Moses] Allah spoke directly.

وَقَفَّيْنَا عَلَىٰ آثَارِهِمْ بِعِيسَى ابْنِ مَرْيَمَ مُصَدِّقًا لِمَا بَيْنَ يَدَيْهِ مِنَ التَّوْرَاةِ ۖ وَآتَيْنَاهُ الْإِنْجِيلَ فِيهِ هُدًى وَنُورٌ وَمُصَدِّقًا لِمَا بَيْنَ يَدَيْهِ مِنَ التَّوْرَاةِ وَهُدًى وَمَوْعِظَةً لِلْمُتَّقِينَ

And in their footsteps, We sent ‘Îsâ (Jesus), son of Maryam (Mary), confirming the Taurat [Books of Moses] that had come before him, and We gave him the Injeel [Gospels], in which was guidance and light and confirmation of the Taurat [Books of Moses] that had come before it, a guidance and an admonition for Al-Muttaqun [the pious].

وَلَقَدْ كُذِّبَتْ رُسُلٌ مِنْ قَبْلِكَ فَصَبَرُوا عَلَىٰ مَا كُذِّبُوا وَأُوذُوا حَتَّىٰ أَتَاهُمْ نَصْرُنَا ۚ وَلَا مُبَدِّلَ لِكَلِمَاتِ اللَّهِ ۚ وَلَقَدْ جَاءَكَ مِنْ نَبَإِ الْمُرْسَلِينَ

Verily, (many) Messengers were denied before you (O Muhammad صلى الله عليه وسلم), but with patience they bore the denial, and they were hurt; till Our Help reached them, and none can alter the Words of Allah. Surely there has reached you the information about the Messengers (before you).

وَتَمَّتْ كَلِمَتُ رَبِّكَ صِدْقًا وَعَدْلًا ۚ لَا مُبَدِّلَ لِكَلِمَاتِهِ ۚ وَهُوَ السَّمِيعُ الْعَلِيمُ

And the Word of your Lord has been fulfilled in truth and in justice. None can change His Words. And He is the All-Hearer, the All-Knower.

Repent and believe on the Lord Jesus Christ.