As far as I know he has no particular Christian concern, but in this post he talks about his decision to say no to a large amount of financial wealth, and why he did so.
From the post, his obvious (to Christians) conclusion:
A big bank account won’t provide the same amount of happiness you’ll get from spending time with the one person you decided you’d rather be with than anyone else. A bigger paycheck is poor compensation for missing out on raising your kids.
Mark's major concern, happiness, is not a bad one, and his chosen way of pursuing it makes sense. For Christians, happiness is not particularly important, but godliness is:
Now there is great gain in godliness with contentment
Incidentally, Mark Shead is the man who put me onto dropbox, which saves me the most inordinate amount of time and anxiety in my daily desire to stay organized and make sure I don't lose data. Click through and use, my friends!