Final answer:
The Council of Nicea declared Jesus as both fully divine and fully human, adopting the Nicene Creed and countering Arianism. This is the opposite of what the question's statement suggests.
Step-by-step explanation:
The statement that the Council of Nicea in 325 A.D. denied that Jesus was fully God and fully human is false. The Council of Nicea actually confirmed the divinity of Jesus Christ and fought against the Arians, who suggested that Jesus was a created being and not consubstantial with God. The council adopted the Nicene Creed, which declared that Jesus was 'begotten, not made' and of the same substance as God (consubstantial), affirming His divine nature.
In subsequent years, the nature of Jesus continued to be a point of contention among Christians, with debates over Monophysitism and Dyophysitism leading to the Council of Chalcedon in 451, which declared that Jesus was both fully human and fully divine without mixture. These decisions were pivotal in shaping Christian orthodoxy and addressing the questions of the Trinity and Christ's nature that challenged religious authority.