How do we know that Jesus Christ was fully God and fully man?

The dual nature of Jesus Christ—fully God and fully man—serves as a cornerstone of Christian doctrine. John 1:14 affirms this by declaring that the Word became flesh and dwelt among us, manifesting the glory of the only begotten Son. In His incarnation, He willingly took on the likeness of sinful flesh without losing His divine essence. This mystery of the God-man is further illustrated through His life, where He experienced human emotions, physical needs, and ultimately, death, while still retaining His divine authority and nature. Scripture reinforces this mystery, confirming that through His humanity, He could relate to our weaknesses while still being the source of salvation as God.