>The Quran argues for itself
Lets see what it argues.
>He has revealed to you the Book with truth. Verifying that which is before it. And He revealed the Torah and the Gospel aforetime a guidance for the people. And He sent the Quran. (Sura 3:3-4)
So not just the Gospel but the Torah were revealed by Allah himself as a guidance for the people, but you claim that Allah couldn't protect the Gospel from corruption, so what He intended to guide instead misguided. This is a strange mindset to have considering the following.
>And Recite what has been revealed to you of the book of your Lord. There is none who can change His words, and you shall not find any refuge besides Him. (Sura 18:27)
No one can change Allah's words as clearly stated in His Eternal Word, which also states that the Gospel is His word. So if any Quran verse states the Gospel was corrupted that would be a direct theological contradiction in Islam, But the actual position of the Quran is that Christians misinterpret the Gospel because Muhammad was literate and only had a vague idea of the Gospel which he got from folklore , which is where you get stuff like Jesus preaching as a baby which comes from the Arabic infancy gospel(a forgery writing centuries after the time of Christ), and Mary being the sister of Aaron because she has the same Arabic name as the sister of Aaron & Moses
Furthermore, sura 7:157 states that Christians had the Gospel at the time of Muhammad.
>Those who follow the messenger, the unlettered prophet, whom they find mentioned in their own [scriptures]-in the Torah and the Gospel-...It is they who will prosper. (7:157)
Putting aside that the Torah and Gospel never mentioned Muhammad in the first place , this would make no sense if the scriptures Christians had access to had already been corrupted. On that note...
>Let the people of the Gospel judge by what Allah hath revealed therein. If any do fail to judge by (the light of) what Allah hath revealed, they are (no better than) those who rebel. (sura 5:47)
>Say: "Oh people of the Books! You have no ground to stand upon unless you stand fast by the Torah, the Gospel, and all the revelation that has come to you from your Lord." (Sura 5:68)
Allah specifically tells Christians to judge by the Gospel, and once again this would be absurd if they were corrupted. We have copies of the Gospel from before the time of Muhammad let alone his time and they contradict it on fundamental theological issues. So judging by the Gospel as Allah commands us to, we can only conclude Islam is false. Why would Allah tell us we have no ground to stand upon unless we stand on a corrupt book?
But wait, there's more. The Gospel is also authoritative for Muhammad himself.
>But if you (O Muhammad) are in doubt as to what we have revealed to you, ask those who read the book before you; certainly the truth has come to you from your Lord, therefore you should not be of the disputers. (10:94)
So Muhammad himself can only confirm the his revelations by checking if they line-up with the Gospel of course he didn't actually check since he couldn't read
. And if you claim the Gospel has been corrupted, then you deny Allah's claim that no one can change His words.
So in summary, if the Gospel is the inspired and preserved word of God then Islam is false because it contradicts Islam, but if the Gospel isn't the inspired and preserved word of God then Islam is still false because it affirms the inspiration and preservation of the Gospel. Either way, Islam is false. In fact, if the Torah contradicts the Gospel or Quran then Islam is false. If any three of these books contradicts even a single other of the three than Islam is false.
However, even without all that, even if Muhammad could read the Bible and adjusted the above verses so they didn't automatically debunk Islam, I still wouldn't believe his heretical fanfiction written hundreds of years after the Gospel.
I still wouldn't believe a religion that encourages it's followers to act like rabid pillaging animals, allows sex with children, rape, and it's followers to lie when it suits them among other things.
I still wouldn't believe a book that says one fly wing has a disease and the other the cure
I still wouldn't believe a religion which calls God the best of deceivers and says He deliberate disguised someone else to look like Jesus so people thought He died, when that would inevitably lead to the belief He rose from the dead when people spotted him after that, which in turn would inevitably lead to the "corruption" of His supposed original teachings.
I still wouldn't believe a prophet who initially thought he was demon possessed, and used to have pagan goddesses in his religion before having a revelation that the previous revelation mentioning them was demonically inspired.
I still wouldn't believe a prophet who plagiarized several different pagan and heretical Arabian folktales and practices.
I still wouldn't believe a prophet who conveniently has a new revelation whenever he wants to do something like take his adopted son's wives or have more wives than Islam allows for anyone else.
I still wouldn't believe a religion who's pattern of moral conduct for mankind was a murderous, depraved narcissistic warlord who had sex with a nine year old girl and got little boys to suck on his tongue.
And I still wouldn't believe a prophet who died feeling like his aorta had been severed when his own book said that Allah would sever his aorta if he was a false prophet.