How do we know that Christ's humanity was sinless?

Christ’s sinless humanity is fundamental to Christian doctrine, affirmed in Scripture where it states that He was manifested to take away our sins, and in Him there is no sin (1 John 3:5). He lived a perfect life, fulfilling the law completely without succumbing to any temptation, a truth stressed in Hebrews 4:15, where it describes Him as being tempted in every way, yet without sin. This perfection is essential for His role as our Savior, for only a sinless sacrifice could atone for the sins of the elect, solidifying the foundation for salvation through grace.