10:17 by the word. In this verse, “word” means, literally, “saying” (same as in Ephesians 6:17, referring to “the sword of the Spirit”). That is, not just the Bible in general, but each individual “saying” is vital to the full understanding of God’s plan. In some manuscripts, “the word of God” is replaced by “the word of Christ.” Since Christ is God, the effect is the same.
10:18 into all the earth. Yes, all men have heard the gospel, even those to whom no preacher has ever gone. Paul here reminds his readers of the same truth he had stressed in Romans 1:20 (see notes on this verse). All men are “without excuse,” since God has left a complete witness in the creation, especially in the heavens. Quoting Psalm 19:4, he stresses that a silent but eloquent witness has gone forth into all lands since “the heavens declare the glory of God [which actually is Christ Himself—Hebrews 1:3; Colossians 1:17] and the firmament showeth His handywork” (Psalm 19:1), day after day and night after night.