The first thing to determine when talking with someone is are they dead or alive to God. Are they dead in Adam or in alive in Christ. Do they have the Spirit or not?
If they are dead they’ll never understand or believe what you say. The things of God are known to us by the Spirit of God (I Cor. 2:8-16). Read the Gospels to see how Jesus responds to those who come to Him who are dead. Or who exhibit no faith.
The dead man, being made in God’s image, can discuss the things of God and discuss them at length. They can read and memorize the Bible. But understanding and believing are different matters.
If they are dead your goal is tell them directly they are dead and what they should do is cry out to God for His Spirit. Jesus tells us to come to God, knocking and asking, and He will give us His Spirit (Luke 11:5-13). If they want ask God for His Spirit then there’s no reason to talk to them.
If they are alive or bear marks of the presence of the Spirit then by all means speak with them. Your goal is seek foundation of their questions. Often Saints ask question without a deep understanding of the Scriptures so you are to take them to a foundational understanding so they can begin to understand how to interpret the scriptures on their own (I John 2:27).