1 John 4:14 New American Standard Bible
14 We have seen and testify that the Father has sent the Son to be the Savior of the world.
It is not only the witness of the Holy Spirit in our lives that confirms we are a child of God, but those who were eyewitnesses of Jesus ministry also testify to who He is. John and the other apostles had seen the risen Christ, they had walked with Him, they had touched Him, He was not merely some story they concocted, they had encountered the risen Christ.
This is why the eyewitness testimony of the apostles was so key to the foundation of the church. It states that the church is built upon the foundation of the apostles and the prophets (Ephesians 2:20). The prophets were God’s spokesmen under the Old Covenant. When God desired to communicate His word to His people, He would speak through the prophets and that which was said was written down. They are the Hebrew scriptures we have today. Also known as the Old Testament.
After the cross it is the apostles through which God operated and built the foundation of the church. Jesus is the chief cornerstone on which all things are built. It is upon His life, His death, and especially His resurrection that is the foundation of all we have in Christianity today. Under the inspiration of the Holy Spirit, the apostles would speak and declare the word of the Lord. It was recorded and written down for all those who would come to Christ to feed upon and grow from.
The testimony is that Jesus is the Savior of the world. He is not merely a good teacher or simply a prophet. He is the Christ. He is the anointed one. He is the only begotten of the Father. He is the way, the truth, and the life. No one is able to come to the Father except through Him. He is not only fully man; He is fully God. He is Jesus and there is no one greater.
This is what our faith is built upon. It is built upon the proclamation and declaration that Jesus is the Christ. He is the savior of the world. Many in this day will doubt or reject the existence of God. But God in this day desires that people would encounter Him, they would see His glory and His power. God desires to manifest this through the lives of His sons and daughters. The more we yield and surrender, the more His life is produced within us. The more His life is produced within us, the impossible becomes possible. The supernatural becomes natural. The risen Christ is manifested through us and we truly become the hands and feet of Jesus.