It is correct now, but the fact remains that the great Confessions of the Reformation were generally Calvinist, some emphatically so. There were three camps - Calvinist, Lutheran, and mystical (Zwingli / Anabaptist / etc.).
If you want to go after the Reformed over it, have at it, but it doesn’t necessarily apply to the rest of Christianity.
The overwhelming majority of American religious at the Revolutionary War were Calvinist. The Anglicans / Episcopals were Calvinist. The Congregationalists were Calvinist. The Presbyterians were Calvinist. The Puritans were Calvinist. The only non Calvinists in America at the time were the Quakers, the various Baptist groups, and the Catholics.
I would agree that Paul’s epistles are where a great deal of theology comes from, but all of it? I’m not so sure.
Some groups are pretty sure.
Moravians weren't Calvinist. They were founded as Unitas Fratrum in Kunvald, Bohemia, in 1457. They were Hussites. They had several well established towns and villages in the backcountry of North Carolina by 1770, Bethabara, Bethania and Salem. Prior to that, they established several Pennsylvania towns, including Bethlehem.
They are noted for their mission work and their music. The very first Fourth of July celebration was held in Salem, NC by Moravians, with music program composed and conducted by Johann Friedrich Peter entitled Psalm of Joy.
Moravians sent missionaries to the Cherokee nation and established several missions. They protested and attempted to prevent Removal, and went along with the Cherokee on the Trail of Tears to aid and to comfort them. Several Brethren had gone ahead, and established a Moravian mission at Tahlequa, Oklahoma, in order to continue ministering to the Cherokee.
Moravians also had a profound influence upon the young John Wesley, and were a primary influence motivating him to establish the Methodist Church.