This article in World, Kill the Christians, is more than a tad unsettling. The short version? In the Afghanistan that our troops are dying for and helping to rebuild, the government is actively working to stop Christians from even being in the country.
One question for Christians should be: can we win more Afghans to Christ with, or without our soldiers being there? I don’t have an answer to that one.
As to the question of whether we can create a liberal democracy in Afghanistan, the answer is almost surely “no.” Not while the nation is under the boot-heel of Islam.