A person's habitual conduct, whether good or evil, reveals the condition of his heart. Eternal life is not rewarded for good living; that would contradict many other Scriptures which clearly state that salvation is not by works, but is all of God's grace to those who believe (e.g., Romans 6:23; 10:9-10; 11:6; Ephesians 2:8-9; Titus 3:5). A person's doing good shows that his heart is regenerate. Such a person, redeemed by God, has eternal life. Conversely a person who continually does evil and rejects the truth shows that he is unregenerate, and therefore will be an object of God's wrath.
The statement first for the Jew, then for the Gentile (lit. "Greek") does not imply special consideration for Jews. Instead, in the light of the divine standard of impartiality (God does not show favoritism), it emphasizes that the entire human race is dealt with by God.
The phrase "the day of God's... judgment" (Romans 2:5) taken by itself may seem to lend support to the idea of a single general judgment of all humanity. However, the Scriptures do not support such a concept. This phrase must be interpreted in conjunction with passages which clearly indicate that several judgments of different groups occur at different times (cf. judgment of Israel at Christ's Second Advent, Ezekiel 20:32-38; the judgment of Gentiles at Christ's Second Advent, Matthew 25:31-46; the great white throne judgment, Revelation 20:11-15). The focus of this passage is on the fact that God will judge all peoples, not on the details of who will be judged when.
(from Bible Knowledge Commentary/Old Testament Copyright © 1983, 2000 Cook Communications Ministries; Bible Knowledge Commentary/New Testament Copyright © 1983, 2000 Cook Communications Ministries. All rights reserved.)