The definition of Christian, is to ,be "Christ-like".
If one measures-UP to the epitome of what God wants for us individually, in the name of Jesus Christ; Then..one may call themselves..
Jehovah's Witnesses are the original Christians. Even though the modern-day name was not coined until the early 20th century, they still go back to the original congregation that Jesus set in motion when he was on earth. Before that they would have been the Israelites when they were Jehovah's chosen nation. All other denominations of christianity come from apostates in the 1st century congregation who began to teach their own doctrines such as helIfire and the trinity. Instead of what God told them to do. They broke away from the congregation and created their own religions. It's all recorded clear as day in the bible for anyone who cares to read it.
Any person who believes that Jesus is the son of God and is their savior is considered a Christian.
If they happen to also believe that Jesus is an alien and did crack cocaine on Tuesdays... they are still a Christian.
There are over 40,000 different Christian-based religions registered with the IRS for tax purposes.
Yes. The only reason they're often rhetorically excluded from mainstream Christianity is because some of their beliefs are *gasp* different. I certainly won't do them that injustice. They believe Jesus Christ is the messiah and the son of God; by definition they're Christians.