Scholars have long understood that the ideology of manifest destiny congealed out of the millennial ideals embedded in American culture. However, they have not fully appreciated that manifest destiny only became a national ideology by overwhelming the arguments that were first voiced during the Monroe administration to resist the incorporation of Texas into the Union. Understanding how the secular ideals of the classical republican tradition were used to resist the inclusion of Texas can help us understand the crystallization of manifest destiny into a theologized ideology in the 1840s.
Rathbun, L. (2001). The Debate over Annexing Texas and the Emergence of Manifest Destiny. Rhetoric & Public Affairs 4(3), 459-493. doi:10.1353/rap.2001.0050.
Rhetoric & Public Affairs