Truly, these times of ignorance God overlooked, but now commands all men everywhere to repent,
Acts 17:30

Has God “overlooked” all sin prior to Christ’s atoning sacrifice? No. All sin is sin, and God holds all people accountable for their sin, no matter who they are, where they live, or when they appear on the timeline.

A better understanding of these words is that God did not send all pagan idolaters the special revelation of either (a) His law (as He did with Israel), or (b) of Christ (as He was doing through the Apostles). All the pagans had was the general revelation Paul referred to in Romans 1—which according to Romans 1-3 relieves no one of accountability to God.

“But now”—referring to in the wake of Christ’s death and resurrection—the revelation of Christ and the gospel is complete and continues to spread ever since.

That God “commands all men everywhere to repent,” is a sober reminder that repentance is an essential element of believing the gospel. It is not an addition to believing, it is an aspect and proof of saving faith.

An Additional Footnote: Repentance does not bring about sinlessness. We continue to wrestle with sin until we are glorified and in Heaven. As we wrestle with sin, we continually confess and repent of our sins. And as we do, we gain continued victory over sin as we sin less often, and less egregiously.