What is the significance of Jesus saying, "I and the Father are one"?

from the old testament

• One of the earliest Jewish confessions is the Shema: “Hear, O Israel: The LORD our God, the LORD is one” (Deuteronomy 6:4). When Jesus claimed to be divine, the Jews believed He was challenging this truth about God. Indeed, God Himself said, “I am the first and I am the last; besides me there is no god” (Isaiah 44:6).
• However, even in the Old Testament, there was evidence of a plurality within the one Godhead. Everything from Genesis 1:26 and its “let us” statement to the Angel of Yahweh speaking as God (e.g., Genesis 16:7–13) hinted at more to the Godhead than simple oneness. God truly is one—there is only one divine nature. And yet, all of Scripture reveals that the divine nature is shared by three distinct Persons, the Father, Son, and Holy Spirit.
• One unique role for God in the Old Testament was, as Creator, His exclusive power over giving and taking life (e.g., Deuteronomy 32:39). Thus, when Jesus spoke about giving eternal life, He was saying He had an ability that belonged to God alone.

from the new testament

• The context for the statement, “I and the Father are One,” found in John 10:30, is part of a larger discussion between Jesus and hostile Jews during the Feast of Dedication (John 10:22–39). When they spotted Him at the feast, they gathered around Him, saying, “How long will you keep us in suspense? If you are the Christ, tell us plainly” (John 10:24). Note that the context indicates that this was not a friendly question. As in other cases, they were looking to entrap Him.
• Rather than replying “yes,” falling into their trap, Jesus said, “I told you, and you do not believe. The works that I do in my Father’s name bear witness about me, but you do not believe because you are not among my sheep” (John 10:25–26). Jesus was saying that the works He had been doing, the works they had all previously seen, already testified as to His identity. However, because they were not His sheep, they didn’t believe what they had seen.
• In this context, by “His sheep,” Jesus means true believers (see all of John 10). Jesus was saying that only those who were His sheep would rightly recognize who He was. Just like real sheep recognize the voice of their shepherd, so do true believers recognize the voice of their Savior Shepherd (John 10:27).
• Jesus then continued that it is to those sheep to whom He gives eternal life (John 10:28). He said that “no one will snatch them out of my hand.” However, He adds, “My Father, who has given them to me, is greater than all, and no one is able to snatch them out of the Father’s hand” (John 10:29). He starts by saying that He holds them but then says that the Father holds them. This is a statement of functional unity, meaning that Jesus and the Father were working in perfect unity. What Jesus did—His works, such as giving eternal life to the sheep and holding those sheep—are all expressions of the Father and Jesus working in unity.
• Jesus then made clear the implication of the unity and the fact that the works they saw should have demonstrated to the Jews that He was from God: “I and the Father are one” (John 10:30). Jesus’ unity with the Father was not happenstance or even Jesus striving to obey the Father perfectly. Instead, it was Jesus sharing the divine nature with God and thus always in perfect unity with Him.
• The Jews understood Jesus’ statement. We read, “The Jews picked up stones again to stone him” (John 10:31). Jesus asked them to clarify their intentions, asking if they were going to kill Him for doing good works (John 10:32). They replied, “It is not for a good work that we are going to stone you but for blasphemy, because you, being a man, make yourself God” (John 10:33).
• Just before they tried to arrest Jesus, He concluded, “If I am not doing the works of my Father, then do not believe me; but if I do them, even though you do not believe me, believe the works, that you may know and understand that the Father is in me and I am in the Father” (John 10:37–38).

implications for today

Being one with the Father means that Jesus not only does what the Father does but that He shares the Father's very divine nature. Jesus and the Father are distinct Persons, yet they are one God, united in essence, power, will, and glory. This differs from the teaching of The Church of Jesus Christ of Latter-day Saints, which holds that the Father and the Son are separate divine beings who are "one" in purpose and will, rather than sharing a single divine essence. However, in John 10, Jesus' claim goes beyond functional unity. His works reveal the Father's works because He shares the Father's divine nature, and the Jews recognized this by accusing Him of making Himself God (John 10:33).

Because the Jews wanted to kill Jesus, they demonstrated that they actually hated God. One cannot deny Jesus and love God (1 John 2:22–23).

If you are married, you can understand this at least to some degree. One cannot tell you they hate your husband or your wife and still be in your good graces! By attacking the one you love, they are attacking you. Of course, no illustration is perfect, but as husband and wife you reflect, in a limited way, the perfect and eternal relationship between the Father and the Son. When your "better half" is attacked, you also feel the attack.

Many people today say they love God, yet, when it comes to Jesus, they either couldn't care less or outright deny Him. This is not the love of God but a rejection of Him. The Bible teaches us that "whoever denies the Son does not have the Father; whoever confesses the Son has the Father also" (1 John 2:23).

Not only is denying Jesus a rejection of God, but it is also rejecting God's only provision for salvation from His wrath (Romans 5:9). God sent His Son so that whoever believes in Him would have eternal life (John 3:16). Since Jesus is the only way the Father has provided (John 14:6), no one can have a relationship with God apart from Him. If you think your relationship with God is secure while rejecting Jesus, Scripture says otherwise. The One who is perfectly one with the Father also declared, "Whoever denies me before men, I also will deny before my Father who is in heaven" (Matthew 10:33).