Ok. So what's the best biblical argument against preterism?
The best... argument 'against' men's doctrine of Preterism is study the whole Bible, and not just The New Testament Books. And I do mean 'study', and not just pass the magic wand over a very short coverage of The Old Testament and call it having covered The Old Testament, which is what Preterist Sunday schools do for children in those kind of Churches. I know, for I was raised in a Preterist type mainstream Church.
The word Preterism is derived from the word 'preter', which means 'what is past'. And that is what men's Preterist seminary doctrine believes, that The Old Testament Books are past history, and even that the Book of Revelation is past history, except for Christ's future 2nd coming. They still believe in Christ's 2nd coming of the future.
That is why most Preterist churches do not preach much end time Bible prophecy. Good works and staying in the Faith instead is mostly stressed.
Today, more than ever in Christian history, it is important to stay in God's Word as written, and let the chips fall where they may. That is the ONLY way to know if a church is actually preaching The Word of God or not. And just preaching one part of God's Word properly while sliding in some doctrines of men is not... the idea of staying in God's Word.
So the believer going into a church especially today not already having studied all of God's Word to know what God says, is at a great disadvantage; that because 5 out of 7 churches will be pushing doctrines of men along with The Gospel Message. That is the number Lord Jesus showed us in Revelation 2 and 3 of the percentage of churches that had false doctrines in them, five out of seven. Only two churches were staying in His Word.
Many brethren cannot believe Christ would allow deceptions to happen in the churches. But that only shows how little they have studied what God's Word reveals. If one decides to listen to men instead of God in His Word, then God will allow that person to be deceived. He is our Heavenly Father, and His feelings can be hurt just like an earthly father who has a child that refuses to listen to their father's advice and direction.
What kind of things can cause a believer to put too much trust in a particular church or preacher instead of verifying everything by study in God's Word with His help? A deceived preacher can fulfill all the 'outward' requirements of appearing righteous and caring, educated, and helpful, etc. They may even speak eloquently, and able to break ideas and concepts down to layman terms, i.e., have a gift for teaching. What most often is not considered by the believer though is that preachers in the mainstream church organizations most often must 'tow-the-line' with that organization's denominational teachings, regardless whether they can be found written in God's Word or not. These facts become obvious to the believer who finally gets down to disciplined Bible study for themselves, asking God's help by The Holy Spirit.