Answer:
He believed that Anglo Saxan race was superior to their skills and dominance in the West.
Explanation:
Josiah Strong was deeply influenced by the social evolutionary theory of Herbert Spencer, which advocates that some people in the Planet have strong skills of governance and dominance because of their original branch. So, based on this statement, Strong argued that the spread of English countries was something divine, and the dominance of other cultures was important to promote their development. But just the white race should do that, because of their strong skills.