>By your own dogma, we were created in God's image, so it follows that the human sense of justice would be similar to God's.
But corrupted by original sin. Try as we might to achieve perfect justice we are unable to do so by our deficient natural reason alone. God's working in divine revelation is raise our standard of consciousness that we might more fully know what it means to be ethical. The culmination of all this is in Jesus Christ, the eternal man, sharing in the Godhood of the Trinity, who delivers through the Holy Spirit a share of the divine wisdom and clairvoyance, such that humanity despite its insufficiencies has a hope through faith to wholly refine its conduct and be restored to its pre-fallen state of glorification within all creation.
>That's rich coming from a Christian
I'm arguing on your ground. I could be a dogmatist and say God's will is God's will, but then we wouldn't have a discussion, would we? It's all the more opportunity to discover what I actually believe in.
>That's true for every moral system.
You admit that a systemic morality is superior to individual caprice, then?
>Your insistence that it's the word of God is only convincing to people who are already part of your religion, or who are predisposed to circular logic (it's the word of God because it says so!)
I wasn't raised Christian, and I questioned the dogmas of the faith for many years. I have the humility to admit that I cannot categorically prove that the Bible is the word of God. It is my conjecture, ultimately, after a critical look at the systemic moralities of the world and of the historical achievements they yielded thereof, coupled with personal reflection on the type of character and of the corresponding values that I consider to be worthwhile to embody in myself if not to see in others, that the modality of thought which is exercised in the schemes of the Christian theology is the optimum. I can't impose my life on you, nor do I have cause to do so. By the traditional doctrine of the church fathers, it's not my call whether you will believe, it is God who ultimately brings one into faith.
Now to degenerate into a total theological shitpost, OP asked why God would necessitate that certain actions need to be performed to achieve redemption rather than independently judging each life on its own. 1. Anyone can justify anything to their own benefit. 2. God maintains a single reality for all. 3. Given free will of the actors therein and point 1, this creates an anarchic space. 4. God has the omniscience to account for the sum of the conflicting interests of the actors present therein. 5. God in sovereignty authority prescribes a canonical methodology for life to effect a particular end. All religion posits some narrative underlying existence, that the universe is meant to tell a certain story, and that human beings operate a certain role within them. The story and its characters change from faith to faith. This gives meaning to life, which would otherwise be a random assortment of events. You could take life as it comes, but as we are driven through the years by the force of time and haunted by the ghost of memory, our experiences construct a story whether we enjoy it or not. Taking in account the multitude of sufferings which are inevitably encountered in a lifetime, the question of what is the meaning of it all, of existence, arises alongside. If we came into life by chance, and all our passions, our thoughts, and our being is an accident, would not our death also be just as meaningless, and ergo suicide is a valid option to escape suffering? Religion's answer is no: there are methodologies of living which incorporate what otherwise would be a passing material phenomenon in biological life into a greater whole. That faith in an objective transcending mortality bids suffering to be borne for what comes after will be even greater glory. The perseverance inspired in the articles of human religion enhance survival. I put forth all this to answer OP's incredulity: this is a secular and materialist justification of religion. However, to simply live, to dodge death, is not enough to argue for any one religion over another. "To be good, it is not enough to be better than the worst," as the Roman Stoic philosopher Seneca put it. For religion to be objectively good it ought not only drive mankind to survive but also to thrive. Each religion exacts from its adherents a certain set of behaviours. Those behaviours may be constructive, or destructive, to achieving a well-functioning society. Each faith has a unique profile of drawback and benefit tradeoffs. It is my affirmation that Christianity asks the least in absurdities and yields the most in abundance of the religious systems of the world. The Christian faith deifies the intangible hopes of humanity for definitive and existential justice. "Human justice" may as well be another name for Jesus Christ, for 'Christ' is literally Greek for redeemer, for justifier, in addition to saviour.