Between 1820 and 1850, some Americans discriminated against Irish immigrants because the Irish?

The correct answer is becasue The Irish were Catholics

Long before they arrived, the poor, hunger stricken Irish met a protestant society which still scorned the excesses of papal control. The Irish threatened to take low paying jobs, and were believed to be carrying diseases, but the scorn they received was largely because of their catholic affiliations. Protestant feared the pope would follow up the catholic Irish with a large army to overthrow the USA government.