Regarding "God has a plan." God has given humans free will. Apart from a few selected individuals (though maybe in the thousands) who were on really important missions, we are free to align our will with the Will of God and follow the Path. The details are not that important. God has a plan for our salvation (whatever afterlife means in practice), and the texts do have enough hints and teachings, which, combined with the presence of the Holy Spirit, can help.

Perceiving "God's plan" is our human way. A mother or father can have plans for their children, etc. Our heavenly Father is the Alpha and the Omega, and probably our whole life is just a timeless fact for Him.

The New Testament is about salvation. It's not a textbook on the "physics" of how the universe works, etc. Thus, it might even be that we each live in our own world, and our will brings the rest of the world to heaven or hell. This is reflected in the very spirit of the Golden Rule Jesus talks about: "Love your neighbor as yourself" (Mark 12:30-31).

As for the "Christian nations," we have yet to witness a single one that has overcome the Tanakh principle of "an eye for an eye, a tooth for a tooth." It does not mean that state-level Christianity is not possible where the Church serves as a purely spiritual power, and people submit to it voluntarily... At the moment this sounds too radical for both West and East though. There is some way "from there to here".