At a bare minimum Tacitus confirms Jesus was a real person who lived in Judea, was executed under Pontius Pilate, and had group of followers called Christians who believed in a “mischievous superstition” that broke out after his execution. I’m trying to think of a good reason not to include Biblical sources, like Paul’s epistles (7 of which are undisputed), when trying to ascertain the beliefs of those who followed this “mischievous superstition” mentioned by Tacitus, but I can’t think of any.