I had heard about Christadelphians in the past, but never knew anything about them except I was told they are a cult that formed in the 1800s. Then earlier this year Christian Research and Apologetics Ministry had an article about what Christadelphians believe and I linked to that.
Christadelphians preach another Christ and another Gospel, as defined by Paul (2 Cor. 11:4), and he said such people should be eternally condemned (Gal. 1:6-9).