Using the word “devout” is problematic in reference to all faiths. It’s one thing for individuals to call themselves that, but it’s another for a reporter to attach the description. It’s a subjective term without a precise meaning to all readers. Words like “serious” or “practicing” or “committed” have similar problems. All these terms mean different things to different people.
When journalists use words like “devout” it implies that the person it is applied to somehow adheres more to a faith’s teachings and practices than others of that faith. And it can too often be viewed as code for fanaticism or extremism or something out of the norm.
Since journalists do not have a direct line into the soul to discern a person’s faith, it is far better to use precise descriptions of a person’s religious practice and observance. For example, “Joe Smith attended Mass every day” or “Jane Smith received a church annulment from her marriage to Joe Smith.” Or “Joe Smith attended worship every week, even when ill.” Or “Jane Smith contributed $200,000 to Trinity Church, where she worshipped.”