It is natural to think that the pronoun they refers to “all who call upon Him” from 10:12 or “everyone” from 10:13. This verse likely does refer to all people. However, it also continues Paul’s criticism of Israel that began in 10:2–3 (see 10:18).
Paul argues that Israel was in a position to understand what God was doing through Jesus Christ. Because of this, Israel was responsible for failing to understand or accept God’s work. Israel was guilty in two ways. First, they failed to understand God’s plan after Christ came (10:3–4). Second, they focused so strongly on the law that they missed Christ when he arrived (9:30–32).