Most important is that you share the Good News (Gospel). This is simple. All these other things may help, but it is the proclamation of the Gospel that transforms minds. See Give Them the Gospel.

Paradigms are very limiting. A paradigm is a fake reality. Each of us has one. To expand our thinking, is quite a challenge. Think of the poor Atheist who has probably been brainwashed by every form of media and every form of indoctrination posing as "education." By revelation, we know that they know God exists. At some point, they decided to listen to voices other than God's Voice. They decided they would not acknowledge Him. Now, they hear His Voice. If by no other means, they hear Him through you, at least when you speak by the Spirit of God. They hear Him when you act by the Spirit of God. Yet, they are constrained by their paradigm, their fake reality. They feel compelled to deny God. Everything outside of that fake reality seems weird to them. Their fake reality seems as if it more real than reality itself. They filter out all information that doesn't fit their fake reality of Atheism.

So, how can you expand their thinking? First, pray for them. No one comes to Christ unless the Holy Spirit draws them.

Here is one of the many things you can do. Perhaps, at the right time, the Holy Spirit will lead you to do this:

Imagine that a person was brainwashed by the media and by the educational system to believe something that wasn't true. Suppose that, as they kept hearing the messages repeated, this formed such an impression on their mind that they just filtered out all facts that contradicted their fake reality. Suppose someone told them about a real experience that didn't fit into their fake reality, and they rejected that evidence. Is there any hope for such a person?

Just supposing for a moment that you were to pray to God over a period of time and ask Him to remove the paradigms in your mind and allow you to see reality as it really is, and suppose that God began to do that and you recognized that He was leading you and showing you a new understanding of reality as it really is.  How would this affect your allegiance to Atheism?

For a moment, just assume that God is real. Imagine that He created everything perfect, but then, the original people He created turned on Him and believed another created being rather than believing Him. Imagine a fallen creation, where the following generations are given over to serve a powerful spiritual entity who has set himself as an enemy of God. Imagine the entire creation in rebellion against the God Who is Love. Being just, God must judge all rebellion. But God decided to redeem His creation back to Himself by personally paying the price of all the rebellion so that He could remain just and yet allow His people to be forgiven and return to Him. Yet, most people never returned. If this were the case, how would the world differ from the world you now see? (Or, what do you suppose that God will do with those who refused to return to Him even though He personally paid the price for their rebellion?)

Just as a mental exercise, imagine God as so powerful and all-knowing that He not only created each and every subatomic particle, along with their counterparts in the spiritual realm which is probably about three times as large as the physical Universe. And imagine that He is currently maintaining the order of everything to that same level of detail throughout the Universe, both the physical realm and the spiritual realm. That's actually what He is doing, though we don't have minds capable of comprehending it. Can you see that this explains why there are laws that we can observe so we can do science whereas the arbitrary assumptions of Naturalism and Materialism provide no such mechanism that would make it possible to do science?

Imagine a person who just made up an arbitrary assumption and then decided to use that arbitrary assumption to act as a filter for every observation and every bit of this person's reasoning. Suppose that person used this arbitrary assumption to make decisions about what other people were experiencing. Since the assumption was arbitrary, the person ended up telling other people that they weren't experiencing what they were experiencing. The arbitrary assumption was the assumption that God didn't exist. Why would anyone be dogmatic about an arbitrary assumption like Naturalism?

Just supposing for a moment that a scientist were to begin all thought processes with the arbitrary assumption that no God exists. Suppose that the scientist forgot that the assumption was just arbitrary and the assumption became entrenched in the scientist's thinking to the point that the scientist began to automatically explain away any evidence for God. What kind of conclusions would a scientist like this make about God?

We are in a day when people are not willing to open their minds. The are actually trained to oppose truth in the Universities. What do you say if they reject Christ and just want to argue?