Eric Orlin says that Roman religion's willingness to adopt foreign gods and practices into its pantheon is probably its defining trait. He goes on to qualify this view by saying this did not apply equally to all gods: "Many divinities were brought to Rome and installed as part of the Roman state religion, but a great many more were not". This characteristic openness has led many, such as Ramsay MacMullen to say that in its process of expansion, the Roman Empire was "completely tolerant, in heaven as on earth", but to also go on and immediately add: "That was only half the story. The other half was a widespread feeling that to slight the [Roman gods was wrong". MacMullen says the single factor determining whether one received 'tolerance' or 'intolerance' from Roman religion was if that religion honored one's god "according to ancestral custom". Christians were thought of badly for abandoning their ancestral roots in Judaism.