Final answer:
Genesis 1:26-27 is significant in the development of the Trinity doctrine because the plural language suggests a multiplicity in the divine nature, which is a foundational aspect of the Nicene Creed. The Trinitarian concept of God as Father, Son, and Holy Spirit is a core belief established by the early Church, particularly at the Council of Nicaea.
Step-by-step explanation:
The significance of Genesis 1:26-27 in forming the doctrine of the Trinity in Christian theology can be linked to the plural language used in these verses. 'Let us make man in our image, after our likeness' suggests a multiplicity in the divine nature, which early Church theologians associated with the Trinitarian concept of God as three persons in one substance. This interpretation aligns with other fundamental Christian beliefs, including the divinity of Jesus and the presence of the Holy Spirit, which are essential elements of the Nicene Creed.
In the second and third centuries, the development of orthodox Christian theology involved theologians like those at the Council of Nicaea, forming a consensus on the nature of the divine being as existing in three distinct persons - Father, Son, and Holy Spirit. This Trinitarian view became a cornerstone of Christian orthodoxy, separating it from rival theological interpretations, such as Arianism, which did not view Jesus as consubstantial with the Father. The Trinitarian doctrine is reflected in the Apostles' Creed, expressing the foundational beliefs of mainstream Christianity.