Osteen is a motivational speaker pretending to be a Christian preacher and he attracts weak minded folk. Any strong conservative fundamental Christian easily spots his errors and stays away. We should warn those weak brothers and sisters.
I’m currently reading a book titled
That You May Know: Assurance of Salvation in 1 John (New American Commentary Studies in Bible and Theology) by Christopher D. Bass. Bass is reformed in his theology.
In chapter 4 of this work, Bass spends a lot of time and effort trying to make the case that 1 John 2:20, 27 is a fulfillment of Jeremiah 31:31-40 i.e.: the New Covenant. The argument is that John in saying that by being anointed (by the Holy Spirit), believers will know “all things” thus the church fulfills Jer 31:34 and by extension the New Covenant is a present reality (in the church). Bass claims that the church, now in receipt of the New Covenant that was once promised to Israel, has a powerful tool in the quest for assurance of salvation in Christ.
It appears from a quick reading to the NICNT commentary of the general letters of Peter and John that reformed theology allows for this interpretation that the church is in receipt of the New Covenant through the work of Christ at the Cross. As a dispie, I find the argument weak, since Jeremiah ch 31 (and To a lesser extent Ezekiel ch 36) specifically mention the recipients of the New Covenant to be ethnic Israel and will include the land promises in the Abrahamic Covenant.
Bass however takes the reformed position to the logical conclusion in his book and basically states that John (1 John 2:18-19) is saying that true believers today do not need to be taught (by their neighbor) to know God since the Holy Spirit will do this. The statements John makes about those who left the faith are simply for illustration and comparison purposes. Those who are truly born again, according to Bass have all of the information they need to know the Lord and fulfill Jer 31 New Covenant terms and conditions. This SolaSaint, would render moot your assertion that John is teaching believers to warn others of doctrinal error, true believers have the truth and know all things, unbelievers have no claim to security and salvation.
I would of course argue that this is not the case, as a believer in the risen Christ I do not claim to know all things. I do know the essentials for salvation; I take John’s warnings to be diligent to in accessing theology and teachings in light of the Scriptures with the guidance of the Holy Spirit.