What would you say if someone asked you to prove that God is good?
(Forgive the long reply, but I have worked extensively on subjects like this over the last 10 years of my life, and have engaged very deeply in Scriptural/theological and philosophical study to answer these questions. I hope you will take the time to read it if you are genuinely interested in the answer and desire to employ what I myself have developed and used on many occasions to satisfy even some of the most stubborn atheists, agnostics and frustrated Christians.)
There is, in fact, a comprehensive answer to this question that should satisfy anyone genuinely seeking an understanding and a certainty of the goodness of God. I have established a scripturally sound cumulative argument that approaches the question with three logically successive points:
1. The human capacity to apprehend objective moral values and duties.
2. The Providence of God in creating the world which would produce the greatest potential good, and,
3. The incarnation and life, death and resurrection of Christ.
Presumably, if someone inquires how we are to know that God is good, we are taking the existence of God for granted, at least for the sake of argument. Thus I will skip the question of competing (false) claims to ostensible sources for morality and answer how we may know specifically that God has revealed Himself truthfully to us as perfect in moral knowledge, character and authority. Pay very close attention to the logic of the following points and their order in this case, designated by numbers that correspond to the three above listed:
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(1.) Since God created us, the universe that surrounds us and everything extrinsic to Himself, everything in all existence derives it's being from God
in its entirety. This includes the entity inside of our flesh we call the brain, which was created to be our fleshly device by which we process our thoughts, emotions and the world around us in our mental interactions with it. This brain in which we contain all of our cognitive capacities and functions was provided by God all of its abilities, not only in its
range of apprehensions of truths but also in its ability to apprehend
categories of truth.
What I mean by
ranges of apprehension is our brains capacity to be used to process information at certain speeds, the amount of information our brain can hold simultaneously, how efficient our thought processes are, how much access we have to our subconscious, etc.; our quantitative abilities. What I mean by
categories of apprehension is what we can apprehend to exist
at all, which we can extend the range of our capacities through to apprehend knowledge about such matters. To provide an example, the
range of our cognitive capacities concerning moral truths would be applied to discriminating between events and actions to determine the moral quality of those events and actions; our cognitive capacity of
categorical apprehension of truth in this instance would be the ability to understand that their even is a moral realm to apprehend
at all.
Thus, if God wanted to deceive us, being the designer of our cognitive functions and capacities in their entirety, He would not even have to try. All God would have to do to deceive humankind is provide them cognitive capacities so limited that they would be absolutely unable to apprehend His deception if He were to flaunt His malevolent motives before their eyes all day long. So what you have to ask yourself is this: If God wanted to deceive me, why would He provide me the cognitive ability to discriminate between truth and falsehood with such accuracy that I would be able to discover His deception? The truth is, doubt exists for only two reasons: Ignorance and free agency. Either we are simply lacking in knowledge and unable to understand why God is abundantly worthy of our absolute trust, or we simply choose to deny Him and His testimony. This decision or ignorant response of doubt never results from rational investigation.
In summary, God is the author of the same cognitive functions that we must use to doubt Him or impose our perspectives onto His creative decree (how we think things ought to be), wholly by the use of the tools provided by His decree of our minds. When you consider this, it should occur to you that there is literally no more of an absurd use of our minds than to use them against the one who constituted them, to doubt what He has revealed of Himself or the perfection of His will.
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It could then be asked, "Why, then, would God create a world that is pervaded by so much evil?" To address this potential confusion if it arises from the first point, we would then demonstrate the providence of God in creating a world of free moral agents from the plethora of options available to Him.
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(2.) In creating a universe that would accommodate truly free moral agents, God would have an infinite number of options available to Him with an equally infinite amount of possible outcomes. From what we know about the nature of God, He would naturally choose to create the world which would produce the greatest possible outcome. What is the greatest possible outcome? There is none other than that world which provides the circumstances which leads the largest number of souls to freely accept the grace of God through the salvation provided in Jesus Christ. From what we know about God's nature, particularly that God is omnibenevolent, omniscient and omnipotent, this can be deductively inferred as follows:
1. Because God is omnibenevolent, He would be desire to create the world which would produce the greatest potential good
2. Because God is omniscient, He would know which world would produce the greatest potential good
3. Because God is omnipotent, He would be able to create the world which would produce the greatest potential good
Therefore the world in which we exist is that which would produce the great potential good. To repeat, this greatest good is the largest number of souls that would freely surrender themselves to God and receive His grace.
To repeat, God would have had a literally infinite number of options present of worlds to create with an equally infinite number of outcomes. By His perfect nature, however, God would not create a world at random in which His will to create concurrently free and absolutely loved creatures was not accomplished. So God would have to narrow His options to feasible worlds which accommodate creaturely freedom and yet lovingly provides the circumstances that permits each person who would freely choose God to do so. Knowing God, once He had narrowed the options to the assortment of great results, He would naturally choose the greatest of these possible outcomes. This is not to say God is predestining our decisions, but the creation of the world which would provide the social, environmental and personal circumstances that are necessary for each individual, in their own times and places as God foreknew, to interact with each other, their environment and God in a way that corresponds to their psychology/personality, ultimately and inevitably leading to the salvation of those who would freely respond affirmatively to God's grace in whatever circumstance they find themselves. In this sense, then, God can literally be said to have elected those who are saved, though their choices as well as those who reject God are entirely free.
As is stated in Acts 17, God placed us within our context because He knew that if given that context we would freely choose to accept Him by the testimony and in-dwelling of the Holy Spirit. It could then be rightly asked "well then could God have not provided a precise set of circumstances that would be those which are necessary to win the soul of every person?", and the answer would be no. For some people, there is no such set of circumstances that would be sufficient for them to freely receive the salvation of Christ by the Holy Spirit's testimony. This is affirmed doubly in the Scriptures. First, in Daniel 12:10 concerning the course through to the end times Jesus says: "Many will be purified, made spotless and refined, but the wicked will continue to be wicked. None of the wicked will understand, but those who are wise will understand." Again, concerning God's providence Paul says in Romans 9:22: "What if God, although choosing to show his wrath and make his power known, bore with great patience the objects of his wrath—prepared for destruction?"
It may also seem confusing to think that God has among His human creation "objects of wrath" which He prepares for destruction, until you comprehend these points and Scriptures collectively. There are some souls which God would create that will freely reject Him under any and all circumstances, but are still necessary in the grand scheme of world history to play a role in drawing all those who will be freely saved into that salvation. God Himself illustrates this wonderfully in His statement to Pharaoh in Exodus 9:15-16: "For by now I could have stretched out my hand and struck you and your people with a plague that would have wiped you off the earth. But I have raised you up for this very purpose, that I might show you my power and that my name might be proclaimed in all the earth."
See Acts 17:26-27, Genesis 50:20, Jeremiah 25:8-14 and Judges 14:4 for more Scriptural examples on the providence of God and how it works.
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After presenting this point, you could not properly present any apologetic case without concluding with an emphasis of and a direction towards the gospel of Christ. In this particular case, you will need to demonstrate that the gospel reveals that God is not removed from human suffering in any sense, including a truly human perspective.
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(3.) The gospel reveals that God is not removed from human suffering, neither emotionally nor physically, nor even perspectively; God is comprehensively acquainted with our suffering (Isaiah 53:3). In the gospel it is revealed that Jesus of Nazareth, the Word (or logos) of God, the second person of the Trinity, incarnated in the body of a man; He assumed the nature of a man and though remaining truly God became also truly man, possessing the divine nature in His Spirit and the human nature in His flesh. Thus, though this man we call Jesus Christ remained perfect in His divine qualities, He subjected Himself to the expression of those qualities by fleshly limitations, though remaining sinless, and to the human experience of our weaknesses.
Christ had to endure the course of the human life, growing from a child into a man, obeying His Father from a truly human perspective. He was submitted like a man to the duties the Father assigned Him in His life and physically and emotionally endured the hardships of human service with the taxing nature of living to glorify, in the flesh, our heavenly Father in a world pervaded by sin, to love enduringly those who did not love Him. Throughout His ministry, Jesus faced hunger, thirst, fatigue, self-denial, rejection, persecution, mockery, hatred, abandonment, physical attacks, brutality and eventually death. To compound the problem, all of this was endured as innocent suffering by a man who had no culpability, and who lived for the exclusive purpose of glorifying His Father through the extension of His grace, mercy, love towards and leadership of lost mankind.
There is no man more acquainted with suffering, and no man less deserving of His fate than Jesus Christ Himself. Yet this is the life Christ endured to provide the unmerrited favour of God towards the world He gave Himself up for; "But God demonstrates his own love for us in this: While we were still sinners, Christ died for us (Romans 5:8)." To emphasize the truly human experience of this suffering, Christ did not endure His road to the cross removed from the depth and perspective of the human experience, but demonstrated intense anxiety, anguish and sorrow towards His impending fate of temporary separation from His Father and physical death (Matthew 26:41-42, Luke 22:44). Despite this, He surrendered Himself to this fate to be offered as the only ransom which is acceptable for our account, the only name under heaven by which we can be saved (John 14:6, Acts 4:12), and was resurrected on the third day following to vindicate His claims before many witnesses, as the gospels testify.
Jesus Christ is the fullness of deity in human form (Colossians 2:9), the complete expression of God and everything He wanted and needed to say to mankind. He is our advocate, our mediator, our saviour and Lord; the Alpha and the Omega, the Almighty. In Christ is the fulfillment of human existence, our purpose, our meaning, our value and our suffering.