I am the bread of life, the ones coming to me, not one hungers and the ones believing to the extent of me not one thirsts (John 6:35)
rather what does it say, 'the word is near you in that your mouth and in your heart, this exists the word of faith that we proclaim (Romans 10:8)
The word mouth is στόμα (stoma) and has a deeper meaning than just speaking words. "... for from the abundance of the heart the mouth speaks" (Matthew 12:34). Jesus said, the heart determines what comes out of the mouth, thus how can evil speak good? How can a thorn bush produce grapes? Therefore the word being in your heart means something has changed in regards to your heart, the word has been planted. James writes, the word of God is implanted having power to save your soul (James 1:21). What happens in salvation first happens with the heart as what comes out of the heart reflects the inner being. Thus Paul states it perfectly, the word of faith is in your heart, and mouth and confessing (homologeó, from homo "same" and lego "speak") is speaking the same, of the believing that occurred in the heart. You are speaking of the same change that occurred in your inner being, "from the abundance of the heart the mouth speaks."
for you have been born again not of perishable seed but of imperishable, by means of the living and enduring word of God (1 Peter 1:23)
The connection between being born again or born anew is inseparable from believing, as Paul writes "you also in him hearing the word of truth, the good news of your salvation, in him also believing, were sealed with the promised Holy Spirit.." (Ephesians 1:13-14). This sealing is through the Spirit which is one of adoption, that we were predestined for, to be adopted as "his own" children, thus to finish the verse Paul writes, "... who [the Spirit] exists the guarantor of our inheritance to the extent redemption of his possession, to the praise of his glory." Jesus said his words were Spirit and truth. This connection between new birth, and believing is inseparable.
Jesus answered them saying to them, this exists the work of God, so that you believe to the extent of him whom he sent (John 6:29)
The people asked Jesus what miraculous sign he would show so that they could believe. These are the same people who saw him heal and cast out demons and who followed him out into the countryside, were they saw he him miraculously feed thousands from five loaves of bread and two fish, and he had walked on water across the sea, and now they are before him asking what sign he would perform so they could believe. Remember the story of Lazarus and the rich man, when both died the rich man pleaded to send Lazarus, raise him from the dead, to warn his sons but he was told "they will not be convinced even if someone rises from the dead" (Luke 16:19-31). Of course Jesus rose from the dead and still many did not believe. Jesus appropriately answered them, believing is the work of God.
There is believing unto salvation and there is faith, they both have the same root word. Faith is assigned to each in measure (Romans 12:3). Jesus is the author and maturer of faith (Hebrews 12:2). All that we have, we have received (1 Corinthians 4:7). Salvation is a gift from God that comes through faith (Ephesians 2:8). Jesus authors and matures our faith, so faith is given and it increases, "rather that faith from hearing, now, that heard through the word of Christ" (Romans 10:17). The gospel is the power of God, unto salvation, to all who believe (Romans 1:16-17). For through proclaiming the gospel the power of God works to the extent that people believe and are saved. Timely are those who preach the good news, as some will hear the gospel and believe, but not all will listen to the good news and believe (Romans 10:15-17).
for the bread of God exists that which comes from heaven and gives life to the world (John 6:33)
The Spirit is one of life, and new birth comes through the Spirit by hearing and believing in the words of Jesus. Paul writes, a person is a Jew inwardly in the new covenant whereby there is is a circumcision of the heart by the Spirit (Romans 2:9). In John 6, we see many turned away from Jesus because of what he said, they must eat his flesh and drink his blood. There was a missing ingredient in their believing, that of the Spirit. Jesus said to those the Father gives him he would turn none away and that they could not come to him unless God granted it and the Spirit was drawing them to him through his words which exist Spirit and truth. They could not believe in Jesus unless God intervened, thus when the people asked what they must do to believe, Jesus said, believing is the work of God.
Read John 6:35-40, Jesus said he was the bread of life, and if you eat you will have life. All you need to do is come to him and believe. But how do you believe? You must come to him, we see this condition. Some of them came to him but did not believe, so there must be more, and his response to this, is all that the Father gives him comes to him... this is the will of the Father that all given to him he will lose none and all who beholds the Son and believes in him will have eternal life. The coming to Jesus must be through hearing his words and the Spirit drawing. So one must come and hear and behold and listen and consider the words of Jesus and through his words the miraculous work of God, the power of God through the gospel, to the extent of salvation, occurs. Certainly. we see the connection between believing through hearing his words and God's power to bring about salvation through the Spirit of life.
I tell you the solemn truth the one believing has eternal life, I am the bread of life... I am the living bread that came down from heaven, if anyone eats of this bread, he lives for all time and the bread which I give exists my flesh, on behalf of life to the world (John 6:51)
The answer to what sign would Jesus perform so that they could believe was "I am living bread that came down from heaven." Moses, the people said, gave manna from heaven so what sign would Jesus give? Jesus said "the ones believing has eternal life, I am the bread of life" (John 6:47-48). Here Jesus connects having eternal life with eating the bread of life. Have you eaten of living bread? Have you tasted that the Lord is good? There is living bread that came down from heaven. They saw him and touched him and proclaim him to us, concerning the word of life, eternal life (1 John 1:1-4).
the one feeding on my flesh and drinking my blood has eternal life ... for my flesh is real food and my blood real drink, the ones who eat my flesh and drink my blood abides in me just as I in them (John 6:53-57)
This offended many of the disciples and they turned away from following Jesus. Jesus responded by saying "it is the Spirit that gives life, not the flesh, the words that I have spoken to you are Spirit and life, but there are some from you who do not believe, for from the beginning Jesus knew who did not believe..." (John 6:63-64). As a kid I heard so many things that I needed to do to be saved, walk down the aisle, raise my hand, surrender my heart, say a prayer, get baptized... you name it I did it. It was later in life that I believed, during a church service, without doing any of the things above, I had come to listen and I heard the words of Jesus and believed. God saved me, by grace through faith, my salvation was a gift of God.
Believing is something amazing from God, I truly do not understand it all, but I do believe it is the work and power of God unto salvation through preaching of the gospel. All we can do is come to Jesus and hear his words then the gospel is the power of God unto salvation. We can only come to him if the Father grants it, the Spirit draws, and believing, the work of God, brings about a sealing of the Holy Spirit, becoming a child of God, born of the Spirit. A child John writes knows the Father and that his sins are forgiven. There are three that testify; spirit, blood, and water. These testimonies are from God and are greater than that of man. No matter what we do, it is these testimonies from God that testify that we have truly believed.