Create a religion, not monster girl religion just a hedonist church that targets lonely people. Using freedom of religion to start to it in the U.S. Then using resources from the demon lord (Like gold), start charities in the 3rd world and spread to them and countries with nukes. Next corrupt the Church's leadership when it gets over 10,000 members and start corrupting rich 3rd worlders like African warlords and businesses that exploit the 3rd world (Make it seem like they just converted). Corrupt Minor government officials (I.E. Police and local Governments). Finally use Demonic energy, power and influence to corrupt American, Religious leaders (Vatican pedos meets Sabbath), and Chinese Government secretly.
The FDA corrupts America food with demonic Energy and China does the same. The Catholic leaders and other religions start to corrupt their followers. Resistance is minimal
Time to train of for 5 years! AND LOSE!