The ego is a wrong-minded attempt to perceive yourself as you wish to be, rather than as you are.
(A Course in Miracles)
The snake tempted Eve in the Middle of the Garden. The symbol in the greatest story ever told is straight-forward enough. Put that way, the first temptation was about sex. Whatever may have happened on that day when humanity was expelled from the Garden of Eden, sex is not a sin but a beautiful creation, as every parent and tantra yoga practitioner will attest to. The sacred act of merging with our soul partner connects us with GOD rather than separating us from HER.
It is also written that the first sin was committed under the Tree of Knowledge. Well, that's a strange idea as well. GOD created all of this Universe - suns, planets, dark matter - for us to explore and experience. Why should we deviate from GOD when we explore what GOD has created for us? The Course of Miracles uses the expression "mis-create" to describe the first sin. So there are activities, thoughts, or intentions, that, deliberate or sub-conscious, point away from love and GOD. We run after our own agenda and are too busy and distracted to notice GOD's KINGDOM. For sex, it is the fantasies, the anticipating, the imagining, that disconnects us from our soul partner and the actual act of making love. In knowledge, it is the scheming, the looking for fame and prestige that disconnects us from the joy and insight of learning.
Going back to the "A Course in Miracles" quote from above, the ego is simply a distorted idea that we have of ourselves and our environment that temporarily disconnects us from the KINGDOM. We see glimpses of GOD, but we literally have to learn to see ourselves and the world with new eyes before we can make HER PRESENCE permanent. Sri Ramakrishna had the following way to describe our temporary separation from GOD. He said that when the boy plays, the mother works on her household stuff. It is only when he throws the toys into the corner and starts wailing when the mother comes over and comforts the child. Similarly, whenever we are running after our deluded desires or run away from our fears, GOD will have to wait for us until we get less self-indulgent. The psychological concept e-g-o can be written as an energy field that temporarily "edges-GOD-out". It is not a permanent psychological fixture, it is just an idea, a flawed perception.
Keep an eye out for HER and enjoy every step of the WAY.