The early Christian martyrs were not only believers of a faith that they would die for. They were witnesses. The apostles were witnesses of Jesus's resurrection and COULD not deny what they knew to be true. That is quite different from someone who has faith in their faith. Although both were martyrs, there's a major difference when you are a witness and know that it is false.
Yasir ibn Amir al-ʿAnsī (Arabic: ياسر بن عامر العنسي) (sixth/seventh century C.E.) was an early companion of the Islamic prophet Muhammad. He is the second martyr in Islam, with the first being his wife, Sumayyah.[1]
https://en.wikipedia.org/wiki/Yasir_ibn_Amir#Death_and_legacy
Here's another quote from that page:
But Yasir and his wife had no one to defend them; they bore no arms, and they were the most defenseless of all the martyrs of Islam. By sacrificing their lives, they highlighted the truth of Islam, and they built strength into its structure.
Do you see that your evidence of the truth of Christianity is exactly the same type of evidence used to prove the truth of other religions? Obviously, this is cannot be evidence of either, or any, religion being true.