Page "First Council of Constantinople" Paragraph 8

Up until about 360, theological debates mainly dealt with the divinity of the Son, the second person of the Trinity.

However, because the Council of Nicaea had not clarified the divinity of the Holy Spirit, the third person of the Trinity, it became a topic of debate.

The Macedonians denied the divinity of the Holy Spirit.

This was also known as Pneumatomachianism.