May 8, 589:
Reccared I, Visigothic King of Hispania, Septimania and Galicia, summons the Third Council of Toledo in what is now Spain.
In the fourth century, a script for the Gothic language had seen the Bible translated into the Visigoths’ tongue, and bishops began converting the Goths to Christianity.
However, when the Visigoths went west, they soon met up with the Latin Christians, who followed a different kind of Christianity than the Visigoths, which saw the Visigoths refuse to convert to Catholicism.
Bishop Leander of Seville organized the Third Council of Toledo. He had been trying to convert the Visigoth kings, and Reccared had done so. The Council saw the Visigoths convert to Catholicism, and introduced Catholic Christianity into the filioque clause (a part of the Nicene Creed, which was drawn up at the First Council of Constantinople in 315).
The council also decided to place restrictions on Jews and try to force them to convert to Christianity, which led to persecution of Jews and antisemitism.
Above, a painting showing Reccared’s conversion to Catholicism.