I debated if this should be an Answer, as I go into specifics more than any general answer. But I think it gives insight to your question by pointing out groups that are not considered to be Christians by many or most Evangelicals, and why.

You specifically mention the Church of Jesus Christ of Latter Day Saints or Mormons as a group that Evangelicals do not consider to be Christian. The doctrinal difference there is basically everything in the Book of Mormon and other Mormon-only books. Evangelicals tend to be sola scriptura, or Scripture Only, and do not think you can add any books beyond the 37 in the Old Testament and 27 in the New.

There is also the issue of the Founder, Joseph Smith, whose claims of divine inspiration they reject. They tend to believe he was a swindler. They think his ideas about Native Americans being Jewish people were just made up. His methods of receiving the divine intervention were not the types of ways that revelation was shown to happen in the Bible, but more how psychics and spiritualists at the time would do, e.g. putting his head in a hat with stones. He also supposedly translated some texts with divine help, but the translations do not match what scholars say today.

As such, they see Joseph Smith as a false prophet, and thus his entire movement as false.

Other groups I can think of that are generally not held to be Christian would be the Jehovah's Witnesses. In this case, the doctrinal issue is quite clear: they reject that Jesus is God.

Some also would exclude those who reject the Trinity, such as Oneness Pentecostals. And some do indeed reject Catholics because they have their Traditions being added to the Bible, and the veneration of Mary and the prayer to saints. Also, Catholics reject Sola Fide, or salvation by faith alone.

Finally, I would say Evangelicals and many other self-identified Christians reject those who identify as Christians because they follow the teachings of Jesus but argue he was just a man. These groups have various names. My high school friend refers to herself as a "Progressive Christian."

I debated if this should be an Answer, as I go into specifics more than any general answer. But I think it gives insight to your question by pointing out groups that are not considered to be Christians by many or most Evangelicals, and why.

You specifically mention the Church of Jesus Christ of Latter Day Saints or Mormons as a group that Evangelicals do not consider to be Christian. The doctrinal difference there is basically everything in the Book of Mormon and other Mormon-only books. Evangelicals tend to be Sola Scriptura, or Scripture Only, and do not think you can add any books beyond the 37 in the Old Testament and 27 in the New.

There is also the issue of the Founder, Joseph Smith, whose claims of divine inspiration they reject. They tend to believe he was a swindler. They think his ideas about Native Americans being Jewish people were just made up. His methods of receiving the divine intervention were not the types of ways that revelation was shown to happen in the Bible, but more how psychics and spiritualists at the time would do, e.g. putting his head in a hat with stones. He also supposedly translated some texts with divine help, but the translations do not match what scholars say today.

As such, they see Joseph Smith as a false prophet, and thus his entire movement as false.

Other groups I can think of that are generally not held to be Christian would be the Jehovah's Witnesses. In this case, the doctrinal issue is quite clear: they reject that Jesus is God.

Some also would exclude those who reject the Trinity, such as Oneness Pentecostals. And some do indeed reject Catholics because they have their Traditions being added to the Bible, and the veneration of Mary and the prayer to saints. Also, Catholics reject Sola Fide, or salvation by faith alone.

Finally, I would say Evangelicals and many other self-identified Christians reject those who identify as Christians because they follow the teachings of Jesus but argue he was just a man. These groups have various names. My high school friend refers to herself as a "Progressive Christian."