Through the Written Word
Most importantly, God has revealed Himself to us through the written word, collectively constituting the Bible. The Scripture is the revelation of God to man, so that man may be able to know God and to know about God. It is given to reveal God's will for our everyday living. "All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be competent, equipped for every good work" (2 Timothy 3:16-17).
The written word also reveals the awesome and unique attributes of God: His sovereignty, omnipotence, omniscience, and omnipresence. We also learn of His character such as holiness, justice and wrath against sin, as well as His grace, love and mercy in the forgiveness of our sins. (I will write about the various attributes of God in some future article/s).
In the Scriptures, we will understand about our origin that we were created in the image of God and endowed with free will, which was gravely abused. Because of this, sin entered the world, and through sin, we are separated from our spiritual union with God. And in spite of our broken communion with God, we will discover from the inspired Word that God has given us a blessed hope that provided the way for us to return to Him-through the redemptive work of the Lord Jesus Christ.
"Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world" (Hebrews 1:1-2). Yes, God has revealed Himself to us through His Son, Jesus Christ, who "is the radiance of the glory of God and the exact imprint of his nature, and he upholds the universe by the word of his power. After making purification for sins, he sat down at the right hand of the Majesty on high" (Hebrews 1:3). He is God in the flesh, the incarnate Son of God (John 1:14) who said "whoever has seen me has seen the Father" (John 14:9); He is manifestation of all the glorious perfection of the person of God in all His attributes.
The greatest need of mankind is only a spiritual and saving knowledge of God. The foundation of all true knowledge of God should be a clear understanding of all His perfections as revealed in Holy Scripture.
To summarize: God has made Himself known through the general though incomplete revelation of His creation. And He has also revealed Himself through the specific revelation of His inspired Word, which in its entirety tells us of His character and of His redemptive plan for mankind through Jesus Christ. "The manifestation of God in nature, His revelation in the Scriptures, and His incarnation in Jesus Christ, assure us that God can be known" (Dr. David Clarke)