...because all men sinned. The interpretation that this phrase proves that Adam is the cause of our being in sin is by exegetically applying the created on earth theory of our creation.Rom. 5:12
Therefore, as sin came into the world through one man, and death as the result of sin, so death spread to all men, [no one being able to stop it or to escape its power] because all men sinned.
1 Cor. 15:22
For just as [because of their union of nature] in Adam all people die, so also [by virtue of their union of nature] shall all in Christ be made alive.
Pre-Conception Existence theology or PCE suggests that all people in HIS image (ie, able to be a proper Bride for HIM), were created in the heavenly Sheol where they heard HIS proclamation of YHWH's divinity and HIS gospel of salvation given to the whole of creation, Col 1:23. The various responses to this call separated all people into 3 broad categories: 1. those who put their faith in HIM as being their GOD and who were therefore elected to salvation and the heavenly marriage, 2. those who rebuked HIM as a liar and therefore a false god who became instantly condemned for this unforgivable sin and 3. those elect who rebelled at the call to come out from among their friends who were now condemned so the judgement could proceed without injury to them, (Matt 13:27-30) but they would not, becoming evil in HIS sight and needing redemption and sanctification as HE had promised them in their election.
Only sinners are sown into this world of mankind, Matt 13:36-39, and Rom 5:12 ...because all men sinned. means that all men sinned pre-earth and sin arrived in the earth with the first sinner to be sown here, Adam. He only led the way, he did not cause their sin.
1 Cor. 15:22 ...in Adam all people die and
Rom. 5:12 ...and death as the result of sin, so death spread to all men,
means that all elect sinners were put under/into Adam's death, not sin, so Christ would not have to die a new time for each and every elect sinner but with all elect sinners in Adam He only needed to die once to cover all elect sinners...NOT that Adam caused all sin to spread over all the earth!