"Unless you are turned and become like children, you will not enter the kingdom of heaven." Matthew 18:3
Why does the Bible insist that we come to God as a child? Because as soon as we become adults, we become foolish and futile in our thinking. Because of their innocence, children tend to be more intelligent than adults. Children tend to be able to reason much better than adults, seeing things plainly that adults feel the need to complicate.
Give a child some Plasticine or Play-Doh and ask him/her to make a man. When finished, ask the child to imagine that his/her creation has just come to life. Tell him/her to imagine it singing and dancing and carrying on. Watch the joy on the child's face as he/she imagines this. Ask the child what he/she would do if his/her creation suddenly turned to him/her and spit in his/her face. The child will take his/her hand and crush his/her creation.
This is what you and I, and every single person on the face of this planet, deserve from God Almighty. We deserve to be crushed like the rebellious insects we are and cast into Hell for all eternity. This is a righteous response from a holy God. It is justice. It is what we deserve. Every single one of us.
Because of God's mercy and grace, and for absolutely no reason whatsoever involving us, from before the foundation of the Earth was laid, God reached out to various individuals and said, "I have loved you." That is, He has aligned them with Himself and allied them with Himself. He chose them out of all others. This is what Malachi 1:1-5 and Romans 9:10-13 are explaining; God's unconditional election.
"The oracle of the word of the LORD to Israel through Malachi. "I have loved you," says the LORD. But you say, "How have You loved us?" "Was not Esau Jacob's brother?" declares the LORD. "Yet I have loved Jacob; but I have hated Esau, and I have made his mountains a desolation and appointed his inheritance for the jackals of the wilderness." Though Edom says, "We have been beaten down, but we will return and build up the ruins"; thus says the LORD of hosts, "They may build, but I will tear down; and men will call them the wicked territory, and the people toward whom the LORD is indignant forever." Your eyes will see this and you will say, "The LORD be magnified beyond the border of Israel!"" Malachi 1:1-5
"And not only this, but there was Rebekah also, when she had conceived twins by one man, our father Isaac; for though the twins were not yet born and had not done anything good or bad, so that God's purpose according to His choice would stand, not because of works but because of Him who calls, it was said to her, "THE OLDER WILL SERVE THE YOUNGER." Just as it is written, "JACOB I LOVED, BUT ESAU I HATED."" Romans 9:10-13