For we know that, if our earthly house of this tabernacle were dissolved, we have a building of God, a house not made with hands, eternal in the heavens. For in this we groan, earnestly desiring to be clothed upon with our house which is from heaven: if so be that being clothed we shall not be found naked.

Our "earthly house" is our physical body which is temporary and will die.  Science may be able to make it last longer, but it will never be immortal.  But we also have an eternal house, our spiritual body and soul which is eternal.  Don't take the second sentence too literally.  Clothing the eternal body means filling out spirit and soul with God's Light.  It has nothing to do with what we are wearing on our physical body.