Does the rapid growth of cities create strategic opportunities for world evangelization and the discipling of nations?

Globalcast asked the question: My responses: 1. I suspect it creates more challenges than opportunities 2. Large populations can be more difficult to reach while rural areas can be addressed in individual detail and churches built over time 3. Much of our ministry work is geared toward rural culture & families, while cities feature urbanism, different transmission methods 4. Lot of missionaries come from smaller towns, more conservative rural areas; megacities are a shock to them 5. Many cities require higher budgets because of more costly standards of living 6. Rapid growth of cities leads to rapid growth in crime & government controls & corruption What do you think? Studies we should link to? Experiences you've had?