Note 17 at Eph. 5:9: In the previous verse, Paul had been promoting holiness because that's the nature of a Christian (see note 15 at v. 8). Now he gives us another reason for living a godly life. It's because the fruit of the Spirit is borne in all goodness and righteousness and truth.

Ungodliness inhibits the growth of the fruit of the Spirit in our lives. That's not because God's love is conditional. His love for us is unconditional. But just as seeds cannot grow without light, so the darkness of ungodliness in a believer's life limits the production of the fruit of the Spirit. If we cultivate a life of hatred, the fruit of love (Gal. 5:22) will not manifest. If we are truly born again (see note 2 at Jn. 3:3, p. 92) that love is present in our spirit, but it cannot flow while we are operating in hatred.