A postscript: It’s entirely possible to explain Christian morality to someone who does not know that God loves her. It’s just that your words won’t mean what you wanted them to mean. Even and maybe especially if she accepts the truth of the moral precepts, the conclusions she draws will be profoundly opposed to the Gospel. If she has never been tempted in this area or has overcome profound temptation (so far) then she may receive your moral teaching with self-righteousness; if she is especially aware of her weaknesses in the areas you’re discussing, she may receive that teaching with despair. The moral truths, taken out of their context in God’s love and mercy, become building blocks for an edifice of cruelty and falsehood.
We all know it when I say it like that. It’s just that we forget how few people genuinely do know that God loves them. It’s weird that we forget, because we’ve all been the person who doesn’t know. But we forget what it felt like.