It is true that the origin of Sin is very difficult to explain. I will no dwell on the apologetic aspect but rather the common sense aspect.
Gen 2:9 said that God planted trees in the garden. In the midst of it is the tree of life and tree of knowledge of good and evil. The specific mention of the two trees means that it is significant.
What is the use of the two trees? We can only imagine by the name given to the two trees. It must be for some use which we cannot imagine. Was it for Adam and Eve, one of them is obviously not (Gen 2:17).
Why then God planted the tree of knowledge and evil? Is it to tempt Adam and Eve? We have no idea. It must be of some use. The use of it is unknown. Adam was put there to work and care for the garden. Is it just for this purpose? God even created a helper for Adam.
God does not want Adam and Eve to live for ever so God banished both from the garden (Gen3:22-23). He also put barriers around the tree of life. This also means that the use of the garden is more than just for Adam and Eve. It is not there to tempt Adam and Eve otherwise the simple removal of the tree of life will suffice.
If the tree of life is specifically mentioned together with tree of knowledge and evil, the protection of one of it when the other is breached is very significant. It means they are more than just there to tempt Adam and Eve. God mentioned that Adam and Eve become like "one of us" and "lest he lives forever" (Gen 3:22). The fact that Adam and Eve are made in the "image of God" (Gen 1:27) and Gen 3:22 means that the trees is probably use by God himself.
When God gave the instruction, Eve was not created yet. Although Eve knows about the instruction, it wasn't given to her directly. The serpent was not known to receive the instruction too. It is acceptable that Eve was punished as she was helper to Adam. Since she is "one flesh" with Adam, the punishment can be applied to her also. However, the punishment is extended to their off springs. This hardly constitute a test of Adam's obedience.
The Serpent plays a part in the coercing of Eve to eat the fruit. However, the instruction is given to Adam and Eve not the serpent. Punishing the serpent seems a bit unreasonable unless the incident is viewed as a crime thus accessory to the crime is also punishable.
If the whole incident is meant to test Adam and Eve, it is strange that the bible deviates from the instruction (Gen 2:17) to describe the creation of animals and birds, the creation of Eve plus the meaning of marriage (Gen 2:18-24) then goes back to the story line in Gen 3.
My conclusion is that the trees are not there to tempt Adam and Eve. Duterte's view is short sighted.
Obviously, the above arguments have no basis. It is just human reasoning.
