Satan, the snake in the garden from before time began, did not lie to Eve, when he caused her to die. God told Adam he would die when he ate the fruit of the knowledge of good and evil (not if, when) and commanded him not to. Eve was told by Adam not to even touch it lest she die.
Satan correctly tells Eve that eating the fruit will not kill her, for God knew eating it would make her like God, in knowing the difference between good and evil. God himself admits in the same story of the Bible that in stealing the fruit from him, Adam and Eve had become like God in knowing the difference between good and evil. She and Adam, based on what, on the face of it, are truthful statements from the snake, eat the fruit. God then prevents them from also eating the fruit of the tree of life, which was in the garden next to the tree of knowledge of good and evil, so that they may not live forever. They, like us, were clearly mortal, because the tree of life, not forbidden them, would have allowed them to live forever, but they chose the tree of knowledge instead; the fall is not a loss of assured immortal life, but a loss of the immortal soul to sin.
What Satan says is mechanically true. Mankind gained knowledge of good and evil, and if not for God, could have also eaten the fruit of the tree of life and lived forever, as beings disobedient to God. God of course knew the Serpent's nature, Adam's nature and Eve's nature, and banished them into time, into the universe we know (as we know that the events in the garden occur before time, before any shrub had grown per the bible), but the world they are thrust into is very much the world of time.
To God, what was certain was based on the acts of God. To Satan, what was true was based on the world without taking into account the nature of God. The property of God, which man was told to look after, belonged to God. And like Prometheus, stealing fire from the Greek gods, Adam and Eve steal the fruit of the tree of the knowledge of good and evil from God and eat of it. They were in the garden to serve God, by tending it, but disobeyed God and stole from him, believing they could one up God by doing so. And it is worth emphasising, the garden was the property of God. Adam was put there to till the land, and Eve to be his helper. They were told they could eat any fruit, but were not permitted to eat of the fruit of the tree of knowledge. They thus took from what was entrusted to them to care for, and stole the fruit they ate from God. Having stolen from God, thinking their scheme was fool proof, Adam and Eve then hide from God, but aren't able to hide from God, nor to deceive him.
Man was not made mortal by his eating of the tree of knowledge, but by his disobedience to God. Satan, in his schemes will be wiley, the wisest of the wild creatures God created, wiser than mankind as well, but his schemes and promises will always be mechanical in nature, and will always exclude the nature of God and the pattern he has set upon the universe. But for God, Satan would succeed in all his schemes, and mankind, rather than being a hybrid of timeous and aeviternal creatures, able to choose between good and evil while we still live, still capable of change, instead, would have become immortal, and remained evil for all time, having eaten of the tree of knowledge, and then the tree of life, but God stopped man eating of the tree of life. Mankind's betrayal of God, and theft from God, was not rewarded.
The anti-Christ is often portrayed by his number, which tends to be linked to the 6th day of creation, and to humankind, to the mechanical universe without God. And pride at its core is the sin of believing in a universe that is purely mechanical, one without the nature of God guiding it. One in which stealing from God is a good idea. The sin of believing we are sufficient, and that our own knowledge and wisdom will bear us out into eternal life, without God.
Any moment you are tempted to do evil, due to the mechanical nature of the universe, due to your knowledge of its ordinary patterns, ignoring the pattern of God, including that of God's wrath, realise that you would have fallen for the same trick Eve did, that the devil isn't lying to you, but if you don't account for God's nature and actions in what you do, you will surely die of your hubris, whereas, in trusting in God and accounting for him, you are capable of gaining life eternal. Man had not been forbidden the tree of life, not until he chose his own schemes over God's plans for him, was this denied him.