There are some things that God cannot do. For example, God cannot tell a lie. He can't do anything that conflicts with His holy character. What God is determines what God does. Since He is holy, all His attributes share in that perfection.
Let me explain what this means to us on a practical level. As a holy God, He is perfect in His righteousness, justice, truthfulness, and faithfulness. His perfect righteousness assures us that we can fully yield to His will because He'll always do what is right. In Genesis 18:25 we read, "Shall not the Judge of all the earth do right?"
His perfect justice means that God will be unquestionably fair. Christians will be rewarded for what they have done (2 Corinthians 5:10), and the wicked will be punished according to their works (Revelation 20:13).
His perfect truthfulness assures us that we can take Him at His word. Numbers 23:19 says, "God is not a man, that He should lie." And finally, His perfect faithfulness tells us that He will never let us down. We read, "His compassions fail not. They are new every morning; great is Your faithfulness" (Lamentations 3:22-23).
We can have absolute confidence in our righteous, just, truthful, and faithful God—because He is holy! —RWD — Richard De Haan
Holy, holy, holy! Though the darkness hide Thee,
Though the eye of sinful man Thy glory may not see;
Only Thou art holy—there is none beside Thee,
Perfect in power, in love, and purity. —Heber
The holiness of God convicts the sinner and comforts the saint.