This is the frame I use to answer the questions I get that start with, "Why would God...?" I get those a lot. When I do and I have a moment to explain my response, I give them the four pieces of this frame before dealing with the particular question. Granted, people can reject the frame or the answer that comes because of it, but I don't have a better way of helping them understand life today and life forever and how they both work if not by this framework. Today, I'll take the fourth piece of the frame and give a brief explanation of it. I titled it Eternal Life.
When I talk about Eternal Life, don't think about clouds and angels and harps and halos. That's a cultural misconception of heaven and has nothing in common with the biblical depiction of Eternal Life. Let me try to quickly define it and provide the application to the "Why God?" question.
First, Eternal Life, according to Jesus in John 17.3, is relationship with God. By implication, then, everyone who lives in right relationship to God through confidence in Jesus Christ is experiencing eternal life right now, today, in this moment. Eternal Life isn't just a quantity of life - a life that goes on and on. It's also a quality of life - life in the eternal realm because God has granted it. Death, then, is a portal through which we step while we keep living (which is why Jesus would say things like those who trust Him never taste death).
Second, Eternal Life is also life as it's meant to be. We weren't created to live 78 years. We were created to live forever. But we don't and can't because of the world we live in, wrecked with sin and its effects. The Bible teaches that Jesus will return at a day of the Father's choosing to do at least two things. He will come to claim His own and take them to be with Him. He will also set everything else right.
So there you have it: relationship and reckoning.
How do those two things help us deal with the "Why God?" questions we face in life? We trusted Him to make us right with Him. The relational aspect also prompts us to trust Him for the other things in life. If not, we find ourselves trusting Him for the big thing(s) but not for the smaller ones. That makes no sense and might say something about our actual level of trust.
Because Jesus is going to set everything right, I can relinquish my right to vengeance and look forward to when God executes the reckoning. I may do so with groaning, like when my friend gets cancer. I may do so with tears, like when death claims a loved one. I may do so with anger, like when a divorce comes despite our best efforts to reclaim a marriage. But I can look forward.
A quote from Miroslav Volf, a Croatian who teaches at Yale Divinity might help conclude:
My thesis is that the practice of non-violence requires a belief in divine vengeance…My thesis will be unpopular with man in the West…But imagine speaking to people (as I have) whose cities and villages have been first plundered, then burned, and leveled to the ground, whose daughters and sisters have been raped, whose fathers and brothers have had their throats slit…Your point to them–we should not retaliate? Why not? I say–the only means of prohibiting violence by us is to insist that violence is only legitimate when it comes from God…Violence thrives today, secretly nourished by the belief that God refuses to take the sword…It takes the quiet of a suburb for the birth of the thesis that human nonviolence is a result of a God who refuses to judge. In a scorched land–soaked in the blood of the innocent, the idea will invariably die, like other pleasant captivities of the liberal mind…if God were NOT angry at injustice and deception and did NOT make a final end of violence, that God would not be worthy of our worship.
I disagree with his stance against non-violence as a necessity, but I do appreciate His overall point: God is going to set the world right and so it frees us to do the things Jesus said and trust Him for justice. I recognize that sometimes we are the instrument of justice, but that's really His choice to us use, not our choice to enforce it.