The Character of God
Holy and merciful, just and forgiving, sovereign and good, held whole
Underneath every other question this site asks lies a deeper one: what is God actually like? Not merely whether He exists, but what kind of God He is. Get that wrong and everything else bends around the error. The Bible's answer is rich, and at first it can seem to pull in opposite directions: God is holy and He is merciful, perfectly just and freely forgiving, utterly sovereign and genuinely good, nearer than your breath and beyond your grasp. The constant temptation is to keep the attributes we find comfortable and quietly file down the rest, sculpting a God in our own preferred image. The living God will not be edited. To know Him truly is to take Him whole.
He is not assembled from parts
Start with something the church has always insisted on: God's attributes are not components He is built from, like ingredients in a recipe. They are what He simply is, wholly, in every single thing He does. He does not merely have love; "God is love" (1 John 4:8). He does not merely possess purity; "God is light, and in him is no darkness at all" (1 John 1:5). This matters intensely, because it means His attributes never compete. His mercy is a holy mercy; His justice is a loving justice. When He acts, all of Him acts at once. So we are not allowed to set His love against His holiness, as if He were sometimes one and sometimes the other. He is always, fully, both.
Holy
If Scripture leans on one word for God above the rest, it is this one, and it is the only attribute the Bible ever raises to the third degree. Isaiah sees the throne, and the seraphim are not crying "love, love, love" or "power, power, power," but "Holy, holy, holy, is the LORD of hosts: the whole earth is full of his glory" (Isaiah 6:3). Holiness is God's utter otherness and His unstained purity, the truth that He is set apart from all He made and from all evil: "there is none holy as the LORD" (1 Samuel 2:2), so pure that the prophet says, "Thou art of purer eyes than to behold evil" (Habakkuk 1:13). Every sentimental, manageable picture of God dies here. He is not a kindly grandfather. He is the Holy One, and the only honest first response to Him is the one Isaiah had: to come undone, and then be cleansed.
Just and merciful, in one breath
Here is the pairing the world most wants to tear apart, demanding either a God too nice to judge or a God too severe to love. God's own self-description refuses the choice. When He proclaims His name to Moses, He says both halves without flinching: "The LORD, The LORD God, merciful and gracious, longsuffering, and abundant in goodness and truth" and, in the same breath, one "that will by no means clear the guilty" (Exodus 34:6-7). Boundless mercy, and unbending justice, in a single sentence. How can both be fully true at once? The Bible's answer is the cross, where God found a way to be, at the same moment, "just, and the justifier of him which believeth in Jesus" (Romans 3:26). He did not waive the justice to show the mercy; He satisfied the justice to pour out the mercy (see the cross).
Sovereign, and good
God is utterly in control. "He hath done whatsoever he hath pleased" (Psalm 115:3); no power checks Him, no plan of His fails. That truth would be terrifying attached to a tyrant, and it is the reason the next attribute matters so much: the One who reigns is good. "The LORD is good; his mercy is everlasting" (Psalm 100:5). Sovereignty without goodness is fate; goodness without sovereignty is well-meant weakness. Held together, they are the only thing strong enough to carry a person through suffering: the hand that holds everything is a good hand. This does not answer every ache of why, but it changes who you are asking. You are not at the mercy of an indifferent machine. You are in the hands of a good and sovereign God.
Unchanging, and faithful
And He does not drift. What He is today He will be forever: "I am the LORD, I change not" (Malachi 3:6), the Father of lights "with whom is no variableness, neither shadow of turning" (James 1:17). This is the ground of every promise He has ever made: a God who changed His mind or His mood could not be trusted past Tuesday, but this God can be trusted past the grave. It is why the man in the ashes of Lamentations could still say, "It is of the LORD's mercies that we are not consumed… great is thy faithfulness" (Lamentations 3:22-23). The God who met your grandparents is the God who will meet your grandchildren, unchanged.
Almost every distortion of God is a true attribute torn loose from the others. Keep only His love and you get a sentimental deity who shrugs at evil and finally cannot be trusted to set anything right. Keep only His holiness and justice and you get a tyrant to be feared and fled, never loved. Keep only His sovereignty and you get fate; only His mercy and you get indulgence. Each of these is a half-God, an idol made of one real trait. The cross is the place where you cannot make that mistake, because there every attribute is on display at once: holiness that will not ignore sin, justice that must be satisfied, love that will not let us go, mercy that pays the whole price itself. Look there, and you see Him whole.
Where this lands
You cannot see God's face, but you are not left guessing at His character, because the fullest revelation of it walked into history. Jesus said it plainly: "he that hath seen me hath seen the Father" (John 14:9). So if you want to know what God is like, the holiness and the mercy and the sovereignty and the faithfulness all together, look at Christ, who was holy and approachable, who told the truth and forgave the guilty, who reigned over storms and wept at a grave. The right response to a God like that is the one heaven gives Him without ceasing: not a shrug, not a debate, but worship. Knowing who He is is the beginning of everything else (see the names that reveal Him, and the one God who is Father, Son, and Spirit).
Related: The Names of God, The Trinity, The Cross, The Image of God, and Loving the Church You Disagree With. Scripture from the King James Version, linked to BibleHub; the words of God are marked in gold, the words of Christ in purple.