Even believers need to be warned about hell. Consider this:Throughout his writings, the apostle Paul not only reminds the churches of their formerly hopeless state; he also warns them of their ongoing danger should they drift from Christ. He says not only, “You deserve hell,” but also, “Make sure you don’t end up there.” Pastor and author Scott Hubbard joined us with a sober reminder that hell should motivate the believer unto holiness.

https://www.desiringgod.org/articles/even-believers-need-to-be-warned