Lao Tzu knew, intimately, this One True God who created the heavens and the earth.
For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them on that day when, according to my gospel, God judges the secrets of men by Christ Jesus.
— Romans 2: 14-16, NIV.
“Will people who have never heard about Christ, ever be saved?”
This is a burning question that every Christian will ask, at least once. And if the response to it was, “No, they’ll not be saved.” Then the consequent reply will be, “why is God so unfair!”
I was a victim of curiosity myself. I questioned salvation and God’s sovereignty. I asked, “if God is sovereign and fair, why didn’t He show Himself to everyone so that everyone has the option to say yes or no.” I thought about it long and hard when I was younger and I never had any answer. Problem was, I asked God with my Bible closed.
God, in His sovereignty, has revealed many hidden mysteries to us. Through the revelation of the Holy Spirit, I’ve come to understand the heart of God and His glorious plans. And every day, I learn to admire His righteousness a little deeper than yesterday.
You see, God looks at the hearts of all people (ref: Jeremiah 17:10, NIV). And if the heart of a certain people was predestined to seek God, then God will definitely be found by him/her, one way or another (Acts 17:26-28, NIV).
And indeed, God was found by people who have lived before Christ. An example of such a person was Lao Tzu (老子). He spent his entire life searching for God. And even though Lao Tzu lived 600 years before Christ in a culture who haven’t heard the gospel until 1600 years later after Jesus, the writings of Lao Tzu in his world-renown publication — Dao De Jing （道德经） — showed that he knew, intimately, this One True God who created the heavens and the earth.
The Dao that can be trodden is not the enduring and unchanging Dao. The name that can be named is not the enduring and unchanging name. (Conceived of as) having no name, it is the Originator of heaven and earth; (conceived of as) having a name, it is the Mother of all things. Always without desire we must be found, If its deep mystery we would sound; But if desire always within us be, Its outer fringe is all that we shall see. Under these two aspects, it is really the same; but as development takes place, it receives the different names. Together we call them the Mystery. Where the Mystery is the deepest is the gate of all that is subtle and wonderful.
— Dao De Jing, verse 1, translated by James Legge, emphasis added .
In fact, the similarities between the Dao De Jing （道德经） and the revelation of John is uncanny. When John wrote about “The Word” in John 1, he was referring to the same Dao（道）as written in Dao De Jing. In fact, the “Dao” in Dao De Jing is “the Word” that cannot be fathomed. It embodies the natural order of the universe to every other thing conceivable .
The Dao is (like) the emptiness of a vessel; and in our employment of it we must be on our guard against all fulness. How deep and unfathomable it is, as if it were the Honoured Ancestor of all things! We should blunt our sharp points, and unravel the complications of things; we should attemper our brightness, and bring ourselves into agreement with the obscurity of others. How pure and still the Dao is, as if it would ever so continue! I do not know whose son it is. It might appear to have been before God.
There was something undefined and complete, coming into existence before Heaven and Earth. How still it was and formless, standing alone, and undergoing no change, reaching everywhere and in no danger (of being exhausted)! It may be regarded as the Mother of all things. I do not know its name, and I give it the designation of the Dao (the Way or Course). Making an effort (further) to give it a name I call it The Great. Great, it passes on (in constant flow). Passing on, it becomes remote. Having become remote, it returns. Therefore the Dao is great; Heaven is great; Earth is great; and the (sage) king is also great. In the universe there are four that are great, and the (sage) king is one of them. Man takes his law from the Earth; the Earth takes its law from Heaven; Heaven takes its law from the Dao. The law of the Dao is its being what it is.
— Dao De Jing, verse 4 & 25, translated by James Legge, emphasis added .
In the entirety of the Dao De Jing, Lao Tzu repeatedly state that he does not know the name of the Dao, neither does he know Who’s Son is the Dao. But deep down, he knows the Dao. He knew that Dao created the heavens and the earth. He knew that the Dao regulates all things. He knew that living water exists . He knew about eternal life . He knew about the empowerment of the Holy Spirit . But He doesn’t know the true identity of Dao.
But we know it. When we look at the struggles of Lao Tzu, we read and we immediately understand who Dao is.
Lao Tzu didn’t know who Dao is. So doesn’t his followers. Hence it is our duty to proclaim to them who Dao is since they are ignorant of the very thing they worship (ref: Acts 17:23, NIV).
Deep down in Lao Tzu’s heart, he sought God. Lao Tzu knew God and he was found by God who had made known to him the manifold mysteries of His creation.
In Lao Tzu’s heart, his conscience bears witness. He had the law of God was written in his heart. It is this law and this conscience that will excuse Lao Tzu on the day of judgement, sparing him from judgement, and enabling him to come into the eternal presence of God.
Will Lao Tzu be saved? Based on his writings and his beliefs, I would think so. But only God who judges the secrets of men by Christ Jesus can determine the fate of his soul.
Not all who subscribes to another faith will be condemned.
 – https://ctext.org/dao-de-jing
 – https://www.daodejing.org/dao.html
 – Dao De Jing, verse 8, “The highest excellence is like (that of) water. The excellence of water appears in its benefiting all things, and in its occupying, without striving (to the contrary), the low place which all men dislike. Hence (its way) is near to (that of) the Dao.”
 – Dao De Jing, verse 16, “Possessed of the Dao, he endures long; and to the end of his bodily life, is exempt from all danger of decay.”
 – Dao De Jing, verse 77, “May not the Way (or Dao) of Heaven be compared to the (method of) bending a bow? The (part of the bow) which was high is brought low, and what was low is raised up. (So Heaven) diminishes where there is superabundance, and supplements where there is deficiency. It is the Way of Heaven to diminish superabundance, and to supplement deficiency. It is not so with the way of man. He takes away from those who have not enough to add to his own superabundance. Who can take his own superabundance and therewith serve all under heaven? Only he who is in possession of the Dao! Therefore the (ruling) sage acts without claiming the results as his; he achieves his merit and does not rest (arrogantly) in it: – he does not wish to display his superiority.”