Why a 'New Earth' If We’re All Supposed to Be in Heaven?
Why is there going to be a new heaven at the Second Coming, and why do we need a new earth? Shouldn't we all be in heaven?
You’re referring to what is presented in Revelation 21:1-5. In short, the phrase “a new heaven and a new earth” refers to what heaven will be like for us as resurrected, glorified human persons. That is, a three-dimensional reality that thus accommodates aspects of our physical earthly experience, though in a glorified manner.
For more on this subject, please watch this short video presentation by Jimmy Akin.