This is the attitude Christians need to have when dealing with those who differ with them in spiritual doctrines:
"I'll pray for you, and I love you, but I don't agree quite the same."
And if you find they don't agree quite the same as you - and can see that they aren't likely to change their views any time soon - then often, it is best to keep communication on those things at a minimum with them. Since God wants us to be peacemakers and also to help keep the unity of Christians in the whole church of God, here on the earth. It does no good to keep telling their views if they are solidly set in their own views on a thing. It is the same way when working at converting unbelievers to Christ. If they aren't interested or open to hearing the gospel message you have to offer - then just pray for them, and let the Holy Spirit work on them.
Jesus preached to crowds a lot. Paul did too, and preached regardless of what opinions might be of some in his congregations. That's a lot like posting spiritual things on the internet. But Jesus didn't explain spiritual things to others personally, unless He knew they had a genuine interest in hearing what He had to say. He always explained such things personally - aside from the crowds - to his disciples.
I looked for testimonies of people who got converted to Christ. I noticed some were more like Luther - in his approach to salvation. Coming out of the Catholic church - he had to learn that works alone can't save anyone. That gave him much relief, and led to his salvation, since he came to see that being saved came largely as a result of God's grace. He rejected the book of James, I've read, as he thought it was not a genuine book of the Bible.
Other testimonies of conversions I read about - were about people who prayed to get converted to Christ, but didn't at first respond to the need to repent of their sins. They didn't have full assurance of their salvation, until they learned the importance of repentance, from the Bible.
As for myself, I thought I got converted, when I was 12 years old. But I denied the need for full repentance towards God. I didn't come to full repentance unti many years later, after I surrendered my life wholly to God - and came to be in the habit of always praying for God to help me be as obedient as was possible. And always doing my best to be as obedient to God as I possibly could, And always repenting daily of my sins. After that big change of my way of following God in my life - I for the first time, had full assurance of being saved. And have continued to have that assurance ever since.
I used to strongly feel the presence of evil forces in my life, and it felt scary. Now, I feel safe - and feel God's presence with me every moment of every day in my life. So much better this way - so glad for this very important improvement in my life!
Eph 4:1-3
4:1 I therefore, the prisoner of the Lord, beseech you that ye walk worthy of the vocation wherewith ye are called,
2 With all lowliness and meekness, with longsuffering, forbearing one another in love;
3 Endeavouring to keep the unity of the Spirit in the bond of peace.
KJV