How mean is it though if the people that rejected it did so because there was no reason to believe it. What a cruel way to sort people into two groups. I don't mean to sound rude but it sounds like he prefers people who don't use their reasoning skills very well.
Not at all rude, it's a valid question.
However, the question assumes a certain standpoint about morality and particularly justice. If you're saying that God is not being fair to some people, you're making a statement about fairness: how do we judge what is fair and not fair, and where do we get the idea of fairness from? If there is no ultimate moral authority or designer of moral laws, how can we even postulate justice? For me, I believe in justice and fairness because I think that there is a set of morals we intrinsically understand (though don't always live by!), and that can only be because humanity is created with that programmed in.
So that's the start of my answer: to challenge the premise you ask from. The second thing I would say that it is evident that God gave humanity free will and that human autonomy is an integral part of who we are and how we are created. In that case, it would be morally unjust of God to force himself on us, simply because of the justice at the heart of God. So to make the evidence too in our face would be forcing us to worship, like a parent not allowing their child to leave home and see the world because they want to keep their child to themselves. Writing 'i am here' in the clouds would mean that we were forced into submission, and worship would not be from the place God desires - our free choice.
I think the evidence is abundant. In cosmology, in nature, in science, in music. In the way we love one another and the way we care for those in difficulties. And not least in the events in history which are backed by robust evidence; the life, death and resurrection of Jesus. Without those this faith really would be based on floaty feelings: this grounds it in historical reality.
Wrt those who have not heard, heard in part or haven't understood, I believe that God is just - that God is justice and love combined, and therefore there will be no unfairness. In the end, it would be unfair to those who reject God to be forced to spend eternity with God, anyway. And God knows the true heart of people and responds to that.
I don't think there is any evidence of God's preference for the unintelligent or easily deluded. God's preference is for every single person who ever lived and ever will, but God will never force love from them.