Things Eternal?

I remember a few years back hearing a line among evangelical people that "the only things that are eternal are God, His Word and souls," so that being the case our entire lives should focus in making Him known by proclaiming His Word by trying to evangelize as many people as possible. There was one book in particular that I remember reading that encouraged its reader to make sure and purchase a house that would require minimal yard work, so that one could focus in on the things that truly are eternal and matter. In a word, we should spend all our energy finding opportunity to "preach the gospel" and to save people from their sin. But is that true? Is that how we should spend all our energy and are those three things (God, His Word and souls) all that will continue on into eternity?

The final book I am working through, due before my May 23rd deadline, is Christopher J. H. Wright's The Mission of God's People. Wright writes this on p. 59, "... although it is gloriously true that sinners are saved through the cross of Christ, it is not actually the whole gospel or the whole achievement of the cross- not according to the New Testament itself." Quoting from Col. 1:15-23, Wright says:

Paul links Christ and creation in the most comprehensive way. Christ was there, of course, as the Son of God, even before creation existed (v. 17). Christ is the source of the creation of the universe (v. 16). Christ is beneficiary or heir of all creation ("the firstborn" [v. 15], "for him" [v. 16]). Christ sustains creation in existence (v. 17). Paul includes creation in the saving power of the cross. Christ has redeemed creation (v. 20). It is vital to see here that the blood of Christ, shed on the cross, is the means of the reconciliation of creation to God, not only of sinners. 

Wright concludes on pp. 60-61:

If, then the cross of Christ is good news for the whole creation, our mission must include being and bringing good news to the whole creation. So our care for creation is motivated not solely by the fact that it was created by God and we were commanded to look after it, but also by the fact that it has been redeemed by Christ, and we are to erect signposts towards its ultimate destiny of complete restoration in Christ. God's redemptive mission includes creation. Our mission involves participating in that redemptive work as agents of good news to creation, as well as to people.