Hi Dave, and thanks for your honest and perceptive question.
I’m not sure where to start because I’m not sure what your assumptions are. But I’ll start where the Bible starts.
God is the loving Creator of the universe. He made everything for us to enjoy, and he made humanity in his image as the pinnacle of his creation (Genesis 1:26-27). So from the beginning, there were two witnesses to what God is like 1) the good world that he made and, 2) humanity created in the image of God. Genesis also says that God’s Spirit is what gives humanity life and existence, ‘he breathed into his nostrils the breath of life’ (Gen 2:7). He planted them in a plentiful garden, with all good things to enjoy. So from the beginning, humanity was dependent on God for everything. In fact humanity, by definition, is less than human without God, since they are the image and likeness of God. But when humanity rejected God, they were ejected from the garden and cut off from the tree of life. This is metaphorical for being cut off from relationship with God, who is the source of all life. This also means that the image of God in us was wrecked by rejecting him.
So God is not just being mean when he tells humanity that without him they will die. Since he’s the source of life, without him there’s only death. However there is still a personal side to it. God made us for personal relationship with him. And he deserves this because he made us. When we make something we normally make it for a purpose, e.g. a paper aeroplane to fly. And we have the right to do with it what we want. If it fails its purpose, we either fix or get rid of it. Since we were made for relationship with God and we have failed that purpose, we aren’t living up to what we were created for. But since God and humanity are persons, God is personally offended when we reject relationship with him.
When God made humanity, he also gave them responsibility and authority to look after the world he had made. Since we rejected him, God not only ejected us from the garden of Eden, but cursed the earth so that it would produce ‘thorns and thistles’, and our work would now be toilsome and painful. The whole created order was stuffed because of our rebellion against God. In addition, human nature was distorted so that we hurt each other and work all other kinds of evil. As you can see, the two things that originally showed us what God is like are no longer reliable indicators of what God is like. We cannot look at humanity because the image of God in us is damaged, and we cannot look at the world because it has been stuffed up by our sin. When we look at humanity and the world, we get ambiguous signals. There is still some good in humanity and creation, so that we can call human birth a miracle and it causes so much joy. But we also see the dark side of humanity and it makes you wonder whether there is a God. You can also look at creation and sing, ‘what a wonderful world’, but on other days you see natural disasters, suffering etc and think ‘if God made this world, how can he be a good God?’. But this is not how God created the world. The world and humanity are no longer reliable indicators of what God is like.
Therefore God’s judgement is actually part of his love. Since he loves the world, he doesn’t like it when we hurt each other and mistreat the world. One day he will bring the whole world to account and bring an end to suffering. We all want to see really “bad” people get justice, but we fail to see that all of us are guilty before God, because we all naturally reject or ignore our relationship with God. We tend to judge whether a person is good or bad depending on how they treat other people. But the more important question is ‘how do we treat God?’ The most important thing is ‘to love the Lord your God with all your heart, mind and soul’. By this definition, all of us are bad people. The secondary, but important things is to ‘love your neighbour as yourself’. And even though we do some nice things, we certainly don’t love others as much as ourselves. God’s judgement is part of his love for his creation, since he won’t let suffering and injustice continue forever.
Still, God did not destroy humanity completely at the beginning. He mercifully delayed his judgement in order to develop his plan to reconcile humanity back to himself. Even though we deserve death and judgement, God did not give up on us. From that time on, he has been working his plan to reconcile humanity and give them the eternal life with him, which they rejected in the garden.
He began rescuing people by saving Israel out of Egypt as a picture of what he was going to do in the future. After many other events revealing his character through the history of Israel, he finally sent his Son Jesus Christ to be the Saviour of the world. He is the full and final revelation of what God is like. By looking at Jesus, you can tell exactly what God is like. The Bible says that ‘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.He 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. (Hebrews 1:1-3). Jesus is the completely trustworthy to know what God is like.
Jesus showed God’s character and purposes by healing the sick, raising the dead, having dominion over the created world (walking on water, stilling the storm etc.) and teaching people about God. By this he shows that he is putting the universe back together again - reversing the curse of Adam and reconciling people to God. As the culmination of his work he died for the sake of the whole world. Since humanity was under the punishment of death for rejecting God, the source of all life, Jesus exchanges his life for ours. Jesus dies in our place so that we will not have to pay the price for our rebellion against God. This is incredible! God loves us so much that he chose to become human and die in our place. Not only that, after three days he rose from the dead as the Lord of the universe. So he has defeated death and offers eternal life as a free gift to all who put their trust in his death and resurrection. We can do nothing to earn our way back to him, but Jesus has done everything to save us.
By looking at Jesus, we can see the very heart of God. In Jesus, God shows his complete, unconditional love for people, and his passionate commitment to reconcile them to relationship with him. We must always make our judgement of what God is like by looking at Jesus. But if we reject Jesus, we are rejecting our only hope of salvation and eternal life. We are rejecting God’s rescue plan. You could look at this and say, ‘God is mean for giving me death if I don’t accept him’, but this would be like saying, ‘the lifeguard is mean for saying that I will die if I reject his attempts to save me from drowning’. The Bible clearly says that God loves us and desires all people to be saved and to come to a knowledge of the truth (1 Timothy 2:4). But if we reject his rescue plan (Jesus), then it is not God who is being mean but us who have made our choice to remain estranged from him. I sincerely hope and pray that God would convince you that these things are true and that you would take up his offer of forgiveness and eternal life with him. Read the gospels or letters in the NT to see if what I’m saying is true.
I hope I’ve answered your question properly. I may have missed some things or not explained them properly so please contact me if you want me to clarify anything or ask any further questions.