Apostle Peter also told us to be mindful of what the OT prophets were given to write...
2 Pet 3:1-2
1 This second epistle, beloved, I now write unto you; in both which I stir up your pure minds by way of remembrance:
2 That ye may be mindful of the words which were spoken before by the holy prophets, and of the commandment of us the apostles of the Lord and Saviour:
(KJV)
The early Church in Paul's days DID have God's Word to read in the Churches; it was the Old Testament, mainly the Hebrew OT and Greek Septuagint (Greek Old Testament). Christ would call Paul to write most of the New Testament Books. But everything that was being fulfilled in their day was already written first in the Old Testament prophets, which is where Christ's Apostles referenced Scripture from when preaching in the New Testament. Prophecy in the OT prophets covers all the way past Christ's future return into God's Eternity.
It's correct that we DO need to ask our Heavenly Father for understanding in His Word, and to check His Word out for ourselves. That's very true. The Holy Spirit will help us in that, but only IF we listen.
Yet how is it that some who claim to have The Holy Spirit can also be deceived, like the five foolish virgins our Lord foretold of?
A Church that uses those verses from John, are they also saying the OT is now fulfilled dead history? Are they telling you Christ's Apostles and disciples did not have God's Holy Writ to read and study? Are they telling you that our Lord Jesus' second coming has already happenned today? Are they telling you we will be gathered to Christ PRIOR to the coming great tribulation? Are they telling you that you don't really need to study all The Bible, or that only a very small part of The Bible now applies to Christians, and the rest will be filled by The Holy Spirit?