“How Do I Know There is a God?”
As it is stated, this could be a question about the existence of God, or a question about human knowledge. Either way, these ideas have been discussed and debated throughout history, and a long description of religious and philosophical positions could be a possible response. But in not knowing the context in which this question was raised, and in seeking to keep it simple, allow me to suggest five brief responses that all deserve further study.
1. Because you can know anything. The possibility of you knowing anything is because God has allowed you to know things, even invisible things. We do not question these other invisible, basic things but rather assume them. Consider mathematical axioms, or human dignity, or the wind. You know and understand them to various degrees,because you see the results of obeying and ignoring them.
2. Because you have been created to know. God has placed in each person a sense of the divine. John Calvin uses this, not as proof for God, but to rebuke ignorance. As a result of sin, man uses this sense of the divine to devise all sorts of false religions instead of knowing the true God as He offers Himself. And yet, we have been created to glorify and enjoy the one and only God.
3. Because you see the signposts. These signposts are His works, and are given to humanity for our benefit. AlisterMcGrath mentions the following signposts in his book, Mere Apologetics: creation, design, order, morality, desire, beauty, relationality, and eternity. You can know God through His works (Psalm 8).
4. Because you have been told. God has been very clear about His existence: In the beginning God created… (Gen. 1:1).People do not decide whether or not God exists. Paul declares to the philosophers in Athens: God, who made the world and everything in it, since He is Lord of heaven and earth, does not dwell in temples made with hands. Nor is He worshiped with men’s hands, as though He needed anything, since He gives to all life, breath, and all things (Acts 17:24-25). The fact that God exists independently of man’s thought or acknowledgement and that He is self-existent is His aseity. God reaches down to people and reveals Himself.
5. Because by the Holy Spirit’s power, you can know with confidence that He exists. He has promised, and many saints can testify of this, that if you seek Him with all your heart, you will surely find Him (Jer. 29:13; Matthew 7:7). And it is not that He is hiding, but He calls you to seek Him. When you call, He will answer, and you will know Him (Jer. 31:34; Acts 17:27). And those who know Him will serve Him.