It's a very convenient dogma for the church. Faith itself is a virtue (according to the people who profit, or make their living, by peddling faith).
But why is faith per se a virtue exactly? Because, according to the Bible, Jesus and God said that it is? But then you have to take it on faith that faith is a virtue. So it's what they call "begging the question", isn't it? Being a "Doubting Thomas" is considered to be a bad thing within mainstream Christian circles, but the very idea that faith itself (belief without evidence) is in fact virtuous per se, is itself inherently unsupported by anything other than dogma and tradition.