The Second Great Awakening began around 1790. It gained momentum by 1800. After 1820, membership rose rapidly among Baptist and Methodist congregations, whose preachers led the movement. It was past its peak by the late 1840s. It has been described as a reaction against skepticism, deism, and rationalism, although why those forces became pressing enough at the time to spark revivals is not fully understood. It enrolled millions of new members in existing evangelical denominations and led to the formation of new denominations.