Rev 21:26-27
In the Old Testament, Isaiah prophesied that only the redeemed would enter the holy way. (Isa 35:8-10)
Isa 35:8 And an highway shall be there, and a way, and it shall be called The way of holiness; the unclean shall not pass over it; but it shall be for those: the wayfaring men, though fools, shall not err therein. 9 No lion shall be there, nor any ravenous beast shall go up thereon, it shall not be found there; but the redeemed shall walk there: 10 And the ransomed of the Lord shall return, and come to Zion with songs and everlasting joy upon their heads: they shall obtain joy and gladness, and sorrow and sighing shall flee away.
Only those who are written in the Lamb's book of life, that is, those who believe in Jesus as the Christ, will enter the sanctuary. (Rev 21:26-27)
Rev 21:26 And they shall bring the glory and honour of the nations into it. 27 And there shall in no wise enter into it any thing that defileth, neither whatsoever worketh abomination, or maketh a lie: but they which are written in the Lamb's book of life.