How come Good and Evil fruit brought from same tree of knowledge in the garden of Eden?
Matthew7:17-18 is clearly a metaphor while the Tree of Knowledge of Good & Evil is also a form of metaphor but since it is clouded with mystery it is the subject of a lot of interpretation.
How can we be sure that the Tree of Knowledge is only a metaphor? Let's look at God punishment in Genesis3:16-19
From the said passages we can see that God punished Adam & Eve and cursed the Serpent and you might not noticed it God cursed the ground too. Why would God cursed the ground and not include the Tree of Knowledge of Good & Evil? Becuase it was not a literal tree. Remember in the New Testament, Jesus cursed the fig tree;
Jesus Curses a Fig Tree and Clears the Temple Courts
Now, it's clear that the Tree of Knowledge of Good & Evil was also a metaphor.
But, what is the connection of the Tree of Knowledge of Good & Evil to the Tree of Life in the Old Paradise?
In the Book of Revelation the fruit of the Tree of Life is Jesus, and eating the Fruit will give one a taste of Eternal Life promised by Jesus in John Gospel Chapter 6 in the Bread of Life Discourse.
>Jesus said to them, "Very truly, I tell you, it was not Moses who gave you the bread from heaven, but it is my Father who gives you the true bread from heaven. For the bread of God is that which comes down from heaven and gives life to the world." They said to him, "Sir, give us this bread always." Jesus said to them, "I am the bread of life. Whoever comes to me will never be hungry, and whoever believes in me will never be thirsty." (John 6:32-35, New Revised Standard Version)
For Catholic this pertains to the Holy Eucharist as written in the CCC1000, that Jesus promised to all believers.
Now, how about the Tree of Knowledge of Good & Evil? What is it?
We can have a good information on the prayer of the Hail Mary, as Mary is the New Eve.
"Hail Mary full of grace the Lords is with you. Blessed are you among women and blessed is the FRUIT OF THY WOMB, Jesus".
Jesus the fruit of the Tree of Life comes from the Pure Womb of Mary the New Eve.
With this reflection, it is noteworthy to mentioned the Poem of St.Hildegard describing the sin of Eve;
"She destroy her womb by her ignorance".(St.Hildegard poem)
From the poem we can contrast that Mary the New Eve bears the Author of Life in Her Pure Womb. The Wisdom of God Jesus was Incarnated in the pure womb.
Adam & Eve on otherhand lacks wisdom, because the Gift of Wisdom can b acquired by a life of humility & obedience.
"The fear of the Lord is the beginning of wisdom."
Satan, offered Eve a short-cut to acquire wisdom by eating the fruit of the Tree of Knowledge of Good & Evil. Eve was beguiled by the serpent to take the easiest route to acquire wisdom, and that is thru disobedience.
Now, since St.Hildegard described the fault of Eve as related to her womb, what can we infer?
I don't want to go further but as believer of St.Ambrose and St.Augustine profound wisdom the Sin of Eve is related to procreation. Why? God punishment to Eve is related to child-bearing which is related to her womb in procreation.
In closing, both the Tree in Matthew and Genesis are both metaphor.
Note: From a pure Catholic point of view on the Tree of Life;
Pope Benedict XVI has said that "the Cross is the true tree of life."
Saint Bonaventure taught that the medicinal fruit of the tree of life is Christ himself.
Saint Albert the Great taught that the Eucharist, the Body and Blood of Christ, is the Fruit of the Tree of Life.
Augustine of Hippo said that the tree of life is Christ: