What is the name of that band that was part screamo and the lead singer was a guy with really long hair for some reason you thought it was anberlin?

The band you're thinking of might be Underoath, known for their screamo and post-hardcore sound, with lead singer Spencer Chamberlain often recognized for his long hair. Anberlin, while also a prominent band in the alternative rock scene, doesn’t fit the screamo label as closely as Underoath does. If the sound you're recalling is more intense and heavy, Underoath is likely the band you’re thinking of.