How do we know God's attributes are holy?

God's attributes are undeniably holy because they reflect His perfect nature. Each attribute, whether mercy, justice, or love, is characterized by purity and perfection. For instance, in Romans 9:15-18, God's mercy is mentioned alongside His sovereignty in hardening hearts, highlighting that both actions are executed in holiness. This duality demonstrates that God's love for some and evident judgment toward others do not compromise His holiness but rather affirm it, as God's actions are carried out with righteousness and in accordance with His divine will.