By eating of the "Tree of Knowledge of Good & Evil," Adam and Eve had in fact gained The Knowledge Of Good And Evil, yet, man could never live in accord with that correct knowledge (Rom 7:21). This is due to the viral Sin infection that was transmitted to man by his believing and receiving the words of the Serpent. A good friend of mine, Peter Dodds of South Africa, often said "Words are the currency of the spirit realm." Words mean something, they powerfully carry good or evil with them. I see the Serpents words as the evil "seed" that bears his life and nature. We know that Jesus is the Word of God, and He is the regenerative life-giving (1Cor 15:45)"seed" of God (1Peter 1:23) for the good.

Paul here describes the dilemma of the believer who does not yet know he is free from Sin's power.

Rom 7:17-24 … it is no more I that do it, but sin that dwelleth in me. 18 For I know that in me (that is, in my flesh,) dwelleth no good thing: for to will is present with me; but how to perform that which is good I find not. 19 For the good that I would I do not: but the evil which I would not, that I do. 20 Now if I do that I would not, it is no more I that do it, but sin that dwelleth in me. 21 I find then a law, that, when I would do good, evil is present with me. 22 For I delight in the law of God after the inward man:  23 But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members. 24 O wretched man that I am! who shall deliver me from the body of this death?

The infection of Sin in Adam has since past from Adam's body to his physical seed, to all generations of mankind. Sin now initially rules every man that comes into the world, being located within man's own Sin infected flesh.

Romans 5:12 Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:

This Sin infection spontaneously brings with it the expressions of the Sin-nature, which are acts of sin, ending in physical death. James 1:15 … sin, when it is finished, bringeth forth death.

All men have "knowledge of good and evil," but apart from possessing Christ's limitless life they lack the kind of life that is adequate to live in accord with that knowledge (Rom 7:17-23). Man had thought he could make himself wise and thus independent of God, as a god (Gen 3:4-5, 3:22) by gaining this knowledge through eating of that tree of knowledge. But actually, man had received the fallen Sin-nature of the Evil One; becoming a slave to Sin.

Only the man who has been redeemed by the shed blood and death of Jesus Christ, and then regenerated by receiving the resurrected "Spirit of life in Christ" can become free from Sin's power, and become as God intended, according to God's "eternal purpose that He purposed in Christ Jesus" (Eph 3:11).

• Jesus' blood was shed for man's sins, to redeem and justify man before God; freeing man from the penalty of sin's sins.

Rom 5:9 Much more then, being now justified by his blood, we shall be saved from wrath through him.

• Then also Jesus' life was given on the cross also to be the death of man's Sin infected Old Self - the Old Man of Rom 6:6 and Gal 2:20. His death was in fact the death to our Old Man. This then makes us from the POWER of Sin in our flesh.

Rom 6:3 Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death?

Rom 6:6-7 Knowing this, that our old man is crucified with him, that the body of sin might be destroyed (Gk. kartargeo, made of no effect), that henceforth we should not serve sin.
7 For he that is dead is freed from sin (Sin, as a noun).

• Christ's resurrected "Spirit of life" is literally given to us at regeneration when we receive Him, equipping us with the identical life and nature of the resurrected Christ. Christ's eternal resurrection life in the believer is able to overcome both Sin and death.

Romans 8:2  For the law (normal operation of) of the Spirit of life in Christ Jesus hath made me free from the law (normal operation of) of sin and death.

These above are the blessed fruit of "The Tree of Life," which is the Cross (tree) of Jesus Christ. The effects of Sin in man are negated, "made of no effect" by the Cross.

Rom 6:6 (Weymouth Bible) … our old self was nailed to the cross with Him, in order That Our Sinful Nature Might Be Deprived Of Its Power, So That We Should No Longer Be The Slaves Of Sin.

Our redemption becomes effective once and for all time the moment we believe to receive reconciliation to God in Christ Jesus.

Christ's life indwells every believer for eternity and is continually effective in the lives of believers so long as they continue to believe in (trust in, cling to, and rely upon) the Christ who indwells their human spirit as their new person.