"The punishment of those who wage war against Allah and His Messenger, and strive with might and main for mischief through the land is: execution, or crucifixion, or the cutting off of hands and feet from opposite sides, or exile from the land: that is their disgrace in this world, and a heavy punishment is theirs in the Hereafter;" - Quran 5:33 (read more)

"And he [Muhammad] had their hands and feet cut off. Then he ordered for nails which were heated and passed over their eyes, and whey were left in the Harra (i.e. rocky land in Medina). They asked for water, and nobody provided them with water till they died (Abu Qilaba, a sub-narrator said, 'They committed murder and theft and fought against Allah and His Apostle, and spread evil in the land.')" - Sahih Bukhari 1:3:63 (read more)

"...this belief [Trinity] is mentioned in the Qur’aan, but that is by way of refutation and proving it to be false, and describing the one who believes in it as a kaafir and mushrik...This is something that is well known among the Muslims, and they are unanimously agreed that the Christians are kaafirs, and even that those who do not regard them as kaafirs are also kaafirs." - Islam Q&A