What were main issues of Nicaea you?

The First Council of Nicaea, held in 325 AD, primarily addressed the Arian controversy, which questioned the nature of Christ and his relationship to God the Father. The council produced the Nicene Creed, affirming the belief in the Trinity and declaring that Jesus is "true God from true God." Additionally, the council dealt with issues of church governance, the date of Easter, and various other ecclesiastical disputes. Its decisions were pivotal in shaping early Christian doctrine and establishing a unified orthodoxy.