What was the Americanism heresy?

I have read online that there was a heresy early on in America called Americanism. What was the fundamental error that Americanists believed?

“Americanism” was a name given to a set of beliefs that many accused the American Bishops of holding. The accusations caused Pope Leo XIII in 1899 to write the letter Testem Benevolentiae to Cardinal Cardinal Gibbons in order to address the concerns that had been raised.

Among the condemndations were:[list]
*] the idea that democracy is better for the action of the Holy Spirit in the Church
*] placing the prime role of the church’s ministry in natural virtues rather than supernatural
*] the idea that individual Catholics can determine the truth of faith independent of the magisterium
*] that faith is a doctrine for speculation like a philosophical theory, to be relinquished or suppressed under any pretext deemed desirable
*] any notion of a “national church” [/list]

Cardinal Gibbons and the American Bishops denied that they held these views or that these ideas were spreading in the American Church. Historians have considered “Americanism” to be a “phantom heresy” born of rumor rather than actual facts. However, while such ideas might not have been prevalent at the beginning of the 20th century they most certainly took root in the American church by the end of the century and Pope Leo’s letter now appears most prescient.

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