Definition and Context
The concept of "Equality with God" primarily arises in Christian theology concerning the nature and person of Jesus Christ, particularly in the context of the doctrine of the Trinity. This doctrine asserts that God exists as three persons—Father, Son, and Holy Spirit—who are co-equal, co-eternal, and consubstantial, yet distinct in personhood. The idea of equality with God is most explicitly addressed in the New Testament, where it is discussed in relation to Jesus Christ's divinity and His relationship with God the Father.

Biblical References

1. Philippians 2:6-7: "Who, existing in the form of God, did not consider equality with God something to be grasped, but emptied Himself, taking the form of a servant, being made in human likeness."
This passage, part of the Christological hymn in Philippians, is central to understanding the concept of equality with God. It emphasizes that Jesus, though existing in the form of God, did not cling to His divine status but willingly took on human form. This self-emptying (kenosis) is seen as an act of humility and obedience, underscoring His divine nature and equality with God while also highlighting His role in the incarnation.

2. John 1:1-3: "In the beginning was the Word, and the Word was with God, and the Word was God. He was with God in the beginning. Through Him all things were made, and without Him nothing was made that has been made."
The prologue of John's Gospel affirms the pre-existence and divinity of Christ, identifying Him as the Word (Logos) who was both with God and was God. This passage is foundational for the doctrine of the Trinity, illustrating the co-equality and co-eternity of the Son with the Father.

3. John 5:18: "This is why the Jews were seeking all the more to kill Him: Not only was He breaking the Sabbath, but He was even calling God His own Father, making Himself equal with God."
Here, the Gospel of John records the reaction of the Jewish leaders to Jesus' claims about His relationship with the Father. By calling God His Father, Jesus was understood to be claiming a unique and equal status with God, which was considered blasphemous by His contemporaries.

4. Colossians 1:15-19: "The Son is the image of the invisible God, the firstborn over all creation. For in Him all things were created, things in heaven and on earth, visible and invisible, whether thrones or dominions or rulers or authorities. All things were created through Him and for Him. He is before all things, and in Him all things hold together. And He is the head of the body, the church; He is the beginning and firstborn from among the dead, so that in all things He may have preeminence. For God was pleased to have all His fullness dwell in Him."
This passage from Colossians emphasizes the supremacy and divine nature of Christ, affirming that all the fullness of God dwells in Him. It underscores His role in creation and His preeminence over all things, further supporting the notion of His equality with God.

Theological Implications

The concept of equality with God has profound implications for Christology and the understanding of the Trinity. It affirms the full divinity of Jesus Christ, asserting that He possesses the same divine nature as God the Father. This equality is not a matter of hierarchy or subordination but of shared essence and glory. The doctrine of the Trinity maintains that while the Father, Son, and Holy Spirit are distinct persons, they are one in essence, will, and purpose.

Historical and Doctrinal Development

The early church grappled with the implications of Jesus' divinity, leading to significant theological debates and the formulation of creeds. The Nicene Creed (AD 325) and the Chalcedonian Definition (AD 451) were pivotal in affirming the co-equality and co-eternity of the Son with the Father, countering heresies such as Arianism, which denied the full divinity of Christ. These creeds have been instrumental in shaping orthodox Christian belief regarding the nature of Christ and His equality with God.

Practical Considerations

For believers, the doctrine of Christ's equality with God is central to the understanding of salvation, worship, and the nature of God. It assures Christians of the sufficiency and efficacy of Christ's atoning work, as only one who is fully God could reconcile humanity to God. It also informs the practice of worship, as Jesus is worthy of the same honor and adoration as the Father.