The only way to truly know what God is like and to know His attributes is through His revelation of Himself in the Bible, God's Word to mankind. Without the authority of the Bible, any attempt to explain the attributes of God would be to open ourselves up to opinion, conjecture and supposition, which are often incorrect, especially when it comes to trying to understand God. The attributes of God, as revealed in the Bible, are crucial to understanding the truth about God, who He is, what He does, and what He is like.
One of God's primary attributes is that of Creator of all things (Genesis 1:1; Psalm 24:1). Nothing that exists came into being on its own, and no process (such as evolution) created anything. As Creator, God made everything according to His perfect plan to reveal and reflect Himself in the creation. Creation was subsequently marred by the fall of mankind into sin, but even the fallen creation still testifies to God's power and genius (Genesis 3:17-18; Romans 1:19-20). The creation speaks of God's attributes and there is no language or speech where its voice is not heard (Psalm 19:1-3).
In addition to being the Creator, God is eternal, meaning He had no beginning and He will have no end. His existence of one of immortality and infinity (Deuteronomy 33:27; Psalm 90:2; 1 Timothy 1:17). Unlike man who changes from one day to the next, God is immutable and unchanging which means He is absolutely reliable and trustworthy (Malachi 3:6; Numbers 23:19; Psalm 102:26-27). God's mind is incomprehensible to mankind. God's thoughts are not our thoughts and His ways are not our ways (Isaiah 55:9). They are so much higher than ours as to make Him inscrutable, unfathomable, unsearchable, and past finding out as far as understanding Him completely (Isaiah 40:28; Psalm 145:3; Romans 11:33-34).
God is unique; He is one God and there is no other (Isaiah 45:6), and He alone is worthy of our worship and devotion (Deuteronomy 6:4). God is completely sovereign over all of life and all circumstances. His plans and purposes will stand and no one can stop Him or say to Him, "What are you doing?" (Job 9:12; Psalm 93:1; 95:3; Jeremiah 23:20). God is spirit, meaning He is invisible (John 1:18; 4:24). God is a Trinity, being equally present in the Father, the Son and the Holy Spirit. He is not three Gods, but one God in three Persons, each the same in substance and equal in power and glory. God is truth, He will always we truthful and, unlike man, He cannot lie (Psalm 117:2; 1 Samuel 15:29).
God is just, although it cannot be said that He is fair as we understand fairness. If He were completely fair, all mankind would be lost and have to spend eternity in hell paying for our sins. But God is not fair; instead, He is merciful and good, so as the second Person of the triune Godhead, He went to the cross to die in our place, taking the punishment that we deserve (2 Corinthians 5:21). God's justice and His righteousness, the quality or character of being right or just, is another attribute of God. He does not show favortism by respecting some more than others (Deuteronomy 32:4; Psalm 18:30). God is omnipotent; His power is unlimited and complete, although He always limits His power by acting in accordance with the rest of His character (Revelation 19:6; Jeremiah 32:17, 27). God is omnipresent (Psalm 139:7-13; Jeremiah 23:23) and omniscient (1 John 3:20), meaning He is everywhere and knows everything, whether past, present, and future.
God's primary attribute, and the one that permeates all His other attributes, is His transcendent holiness. His holiness is what separates Him from all moral defilement. God is as a consuming fire and His holy wrath against sin is to be feared (Hebrews 12:29, 10:27, 31). His holiness is tempered by His grace which offers goodness, kindness, mercy, and love to those who do not deserve it.