Jesus answered, “The work of God is this: to believe in the one he has sent.”
1 John 3:21-24
Dear friends, if our hearts do not condemn us, we have confidence before God and receive from him anything we ask, because we keep his commands and do what pleases him. And this is his command: to believe in the name of his Son, Jesus Christ, and to love one another as he commanded us.
I like your quote from John 6, but like Paul Harvey used to say, here is the rest of story: (Sometimes quotes are fine, but often you leave out the context and misunderstand what Jesus teaches). Many say that they believe, but do not accept the Truth of God and follow His path.
The Bread of Life Discourse.
22* The next day, the crowd that remained across the sea saw that there had been only one boat there, and that Jesus had not gone along with his disciples in the boat, but only his disciples had left. 23* Other boats came from Tiberias near the place where they had eaten the bread when the Lord gave thanks. 24When the crowd saw that neither Jesus nor his disciples were there, they themselves got into boats and came to Capernaum looking for Jesus.
25And when they found him across the sea they said to him, “Rabbi, when did you get here?” 26Jesus answered them and said, “Amen, amen, I say to you, you are looking for me not because you saw signs but because you ate the loaves and were filled. 27Do not work for food that perishes but for the food that endures for eternal life,* which the Son of Man will give you. For on him the Father, God, has set his seal.”l
28So they said to him, “What can we do to accomplish the works of God?” 29Jesus answered and said to them, “This is the work of God, that you believe in the one he sent.”
30So they said to him, “What sign can you do, that we may see and believe in you? What can you do?m 31* Our ancestors ate manna in the desert, as it is written:n
‘He gave them bread from heaven to eat.’”
32So Jesus said to them, “Amen, amen, I say to you, it was not Moses who gave the bread from heaven; my Father gives you the true bread from heaven.o 33For the bread of God is that which comes down from heaven and gives life to the world.”
34p So they said to him, “Sir, give us this bread always.”
35* Jesus said to them, “I am the bread of life; whoever comes to me will never hunger, and whoever believes in me will never thirst.q
36But I told you that although you have seen [me], you do not believe.r 37Everything that the Father gives me will come to me, and I will not reject anyone who comes to me, 38because I came down from heaven not to do my own will but the will of the one who sent me.s 39And this is the will of the one who sent me, that I should not lose anything of what he gave me, but that I should raise it [on] the last day.t
40For this is the will of my Father, that everyone who sees the Son and believes in him may have eternal life, and I shall raise him [on] the last day.”u
41The Jews murmured about him because he said, “I am the bread that came down from heaven,” 42and they said, “Is this not Jesus, the son of Joseph? Do we not know his father and mother? Then how can he say, ‘I have come down from heaven’?”v 43Jesus answered and said to them, “Stop murmuring* among yourselves.w 44No one can come to me unless the Father who sent me draw him, and I will raise him on the last day. 45It is written in the prophets:
‘They shall all be taught by God.’
Everyone who listens to my Father and learns from him comes to me.x 46Not that anyone has seen the Father except the one who is from God; he has seen the Father.y 47Amen, amen, I say to you, whoever believes has eternal life. 48I am the bread of life. 49Your ancestors ate the manna in the desert, but they died;z 50this is the bread that comes down from heaven so that one may eat it and not die. 51I am the living bread that came down from heaven; whoever eats this bread will live forever; and the bread that I will give is my flesh for the life of the world.”a
52The Jews quarreled among themselves, saying, “How can this man give us [his] flesh to eat?” 53Jesus said to them, “Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you.
****54Whoever eats* my flesh and drinks my blood has eternal life, and I will raise him on the last day. 55For my flesh is true food, and my blood is true drink. 56Whoever eats my flesh and drinks my blood remains in me and I in him.
57Just as the living Father sent me and I have life because of the Father, so also the one who feeds on me will have life because of me.b 58This is the bread that came down from heaven. Unlike your ancestors who ate and still died, whoever eats this bread will live forever.” 59These things he said while teaching in the synagogue in Capernaum.
Check out John 3:21
But whoever lives the truth comes to the light, so that his works may be clearly seen as done in God.p
1John 3;22
and receive from him whatever we ask, because we keep his commandments and do what pleases him.n