The greatest opposition to the work of the Lord is not the unrepentant heathen. No, rather it is those who were once blessed with light and then turned away from their enlightenment. Which unfortunately for members of Christ's church, that means the greatest opposition is among us.
Taking this a step further, my greatest opposition to progress is not external, its internal. It is myself and that tendency to think that because I have already been enlightened once, I am well enough alone.
But "great faith has a short shelf life," (see