Do These Beliefs Cancel Each Other Out?

I received this email from a Muslim recently. He agrees with me that Christianity is wrong, but rather than being an atheist he thinks I should be a Muslim. Just look at how sure he is about reminds me of how sure Christians are of their faith too.

I totally agree that the trinity really makes no sense whatsoever, how can three equal one, and that is what leads to atheism in many Christians. I just want you to know if you ever experienced Islam this is the only true religion that makes sense. There are many former Christian preachers and fellow Christians that have come to Islam. If you truly want to find out the truth please give Islam a chance. Please don't compare Islam to what you hear all over the media because it is completely not true.

I just want to let you know that all the questions are truly answered in Quran. There are preachers and ministers coming into Islam. So just ask yourself truly why are they coming to Islam? If you’re looking for the true religion please check this out. We believe Jesus was a prophet not a god. That’s what led to atheism. Don't just go by what you hear in the media. Also there is a lot of scientific miracles in the Quran to take a look at that haven't been proven wrong.
For what it's worth here are my thoughts when I received this e-mail:

David Hume argued that competing religious claims of miracles "cancel each other out." That is, if competing religions offer up testimonies of the miraculous as support for their faith, then testimonies of miracles themselves cannot provide the basis for religious beliefs. Why? Because these testimonies cancel the credibility of each other out.

The late Ronald Nash said this is probably the strongest of Hume's four subsidiary arguments. [Faith & Reason, p. 238]. Richard Swinburne criticized Hume by arguing that competing religious claims only cancel each other out if the proclaimed miracles of each religion did in fact occur, and if these purported miracles are used to establish the truth of each of these separate religions (since there is nothing prohibiting God from doing a miracle out of kindness to anyone of any faith). [The Concept of Miracle, 1970, (pp. 60-61)].

But listen to what Hume actually said: "This not in reality different from the reasoning of a judge, who supposes that the credit of two witnesses, maintaining a crime against anyone, is destroyed by the testimony of two others, who affirm him to have been two hundred leagues distant, at the same instant when the crime is said to have been committed." [An Enquiry Concerning Human Understanding, Section X]

For Hume this is an epistemological problem, and a credibility problem. Against Swinburne, who claims the force of Hume's argument only works if the proclaimed miracles of each religion did in fact occur, the question in Hume's mind is how he can even know whether or not both miracles occurred, since the credibility of both is suspect. And as far as these purported miracles being used to establish the truth of each of these separate religions goes, how about the claim that Muhammad was miraculously inspired to write the Koran (where it states Jesus did not rise from the dead), and compared that with the Christian claim that Jesus did rise from the grave?

Hence, the Muslim faith does indeed "cancel out" the credibility and epistemological significance of Christianity, and vice versa.