How can muslims claim that Muhammad is a prophet?

You are 100 per cent correct. The Bible has clear and explicit instructions to be wary of the False Prophet, i.e. the wolf in the sheep's clothing...the thief in the night.....check out Daniel & the revelations for clear indications of knowing the characteristic of the False Prophet, the mark of the beast! You do not need to read between the lines to read the truth about the False Prophet' in the Bible...just read the Bible in a politically incorrect manner to see the truth! Prophets of God do not fear ridicule or criticism...Prophets of God do not command their followers to Kill their critics.....Prophets of God do not demand subservience at the point of a sword! Prophets of God do not speak ambiguity and abrogate the original words they claim came from God! Prophets of God do not seek to break the original covenant of god and his laws but come to fulfill the law in continuation with the earlier books and not in contradiction and claims that God allowed his earlier books to be contaminated/corrupted!! The Deuteronomy is very clear about checking out whether a Prophet is a true or false...simple litmus test for beginners is to know a tree by its fruits...Just look around the Islamic world and see the havoc & turmoil its poisonous teachings has done to its own people because of the basic fundamental flaw in Islam of glorifying & sanctifying violence. You may color violence with whatever sanctified political correct names, i.e. holy wars, etc but the fact remains that it cannot hide its hideous face and its effects on the Islamic world. No doubt the Islamic world is ridden with under education, poverty, dictators, barbaric antiquated anti-secular sharia laws.