The most difficult ones are those who are adamant about what they believe, those who can provide no sound Biblical doctrine for what they believe yet will not accept the truths of the Scriptures when offered to them. In fact, they will rebuke you for doing so.
“Professing themselves to be wise, they became fools,” (Romans 1:22)
None of us who have been born-again know all the truth of course, but that which we are assured of by the Holy Spirit we are not only to expound upon, but to stand firm upon. Those who defend the truths of the Word of God are those who are persecuted for His sake.
The person you are speaking with may attempt to tempt you into just agreeing to disagree. Do not do that. Never agree to disagree when it comes to the Word of God, let them believe what they will if they will not listen, if they continue to deny known truths, but do not give them the easy way out, you stand firm.
“If the world hate you, ye know that it hated me before it hated you.” (John 15:18)
“Am I therefore become your enemy, because I tell you the truth?” (Gal. 4:16)
My friends, if you do not have that beam in your eye, you are to help your brother if he has a speck in his. Before you stop casting pearls before swine, you best be sure this is not a brother in Christ though, you need to know if that person is an unrepentant soul who simply refuses to hear truth, or a weaker brother who has yet to understand what has been offered to them. The wise man will be able to discern between the two and will give allowance to time if indeed they are weaker, or unlearned in this regard, in the subject matter at hand.
There is little of the fear of God in this world today, most people live for the temporal, for the immediate gratification of the desires of their flesh, for the continuance of life and its selfish pursuits, and for them the Word of God is irrelevant. It takes a very hard crash for some before they will heed the call. Others have been deceived, brainwashed over a long period of time, heeding and listening to doctrines of devils.
“But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.” (Gal. 1:8)
This truth was important enough that Paul by the Holy Spirit repeated it twice. Those who do so are accursed, they will not listen much less hear, the truths of the Scriptures are hidden to them by their own design, and they will accept no alternative to the lies they have become accustomed to.
We like to believe, and wrongly I will say, that there is hope for all. The other man on the cross next to our Lord died in his sins, there are those the Almighty has given over to a reprobate mind, some are vessels fitted for destruction, for some, He has stopped knocking on the door of their heart. You must be able to tell the difference, and accept these facts, these truths as well.
“For many are called, but few are chosen.” (Matt. 22:14) They profess to be wise, yet they are fools.
“For they that are such serve not our Lord Jesus Christ, but their own belly; and by good words and fair speeches deceive the hearts of the simple.” (Romans 16:18)
It isn’t easy to accept, especially when it is a loved family member, but you must understand this truth as well, not everyone is going to heaven, in fact, most are going to be in the Lake of Fire for all eternity.
When you are speaking to another human being, pay attention to what they say, pay close attention, you need to be able to discern if the light of Christ is within them, or if they are on fire.