Tradução de "unsympathetic source''

Olá pessoal! Vejam o texto abaixo:

If a source that is unsympathetic or even hostile toward the Christian faith provides a report that agrees with the Christian reports, we can have more confidence that the event had occurred, since the unsympathetic or hostile source would not have the bias carried by the authors of the Christian reports. This is called the criterion of UNSYMPATHETIC SOURCES.

Estou em dúvida sobre a tradução de unsympathetic sources. Como vcs traduziriam?