You focused in on one sentence, and just skipped over everything else, including a quote from them, that says that the "lion's share" of giving by evangelicals is to churches.
I am skeptical of polls by partisan sources. There are subtle and ways that results can be biases, even if there's no conscious intent to do so. Even so, the Barna data doesn't support your point.
In 2003 the U.S. contributed 0.16% of GDP to foreign aid, which is at the bottom of the barrel versus other industrialized countries, and that even that aid comes with a lot of strings attached. I'm not saying that most other countries are super generous, though.
Here's a chart of OECD data of Official Development Assistance (ODA) from 2001 to 2004. A few secular European countries are doing reasonably well. The U.S. is not--not at all. It's good to see that foreign aid has been on an upward trend, but a lot of it is going to the "war on terror", Israel, and Egypt.