The Bible describes heaven or the eternal state in great detail in Revelation chapters 21–22. Nowhere in those chapters is the possibility of sin mentioned. In fact, we have the promise that, in the eternal state, we will never experience death, sorrow, crying, or pain (Revelation 21:4)—the absence of those things is proof positive that sin is also absent, since those things are the product of sin (see Romans 6:23).

The sinful will not be in heaven but in the lake of fire (Revelation 21:8). Nothing impure will ever enter heaven (Revelation 21:27). Outside of heaven are those who sin (Revelation 22:15). An Old Testament prophecy also assures us that the Kingdom of God will exclude sinfulness:
“A highway will be there;
it will be called the Way of Holiness;
it will be for those who walk on that Way.