Seminary terms like Replacement Theology (or Supersessionism) are nothing but tethers that limit a more full understanding in all of God's Word. (A tether is like a pole in the ground with a rope tied to, and whatever is tied down can only reach to the limits of that rope and no further). This is why our Lord Jesus warned us about the leaven doctrines of men with His parable of the new wine and old bottles, and what He revealed to His disciples in Matt.16 about the many baskets of bread fragments gathered up after the five (Grace) loaves were sent out.
The Jews hate Replacement Theology because they see it as an encroachment upon God's promises to the nation of Israel that He said will be established forever per Jer.31. Dispensationalists don't like it because it conflicts with their Pre-Tribulational Rapture theory, because they believe Christ's Church is raptured to Heaven prior to the tribulation while the seed of Israel stays on earth to go through the coming tribulation, and existing on earth for Christ's Milennium reign while the Church is in Heaven with Him. And then many in Christ's Church that do believe it fail to understand Paul in Romans 11 about the seed of Israel being blinded in part for this world so The Gospel would go also to the Gentiles, with that blindness being eventually removed with Christ saving them per Rom.11:25-27; nor why Paul would apply the term "commonwealth of Israel" from Eph.2 to believing Gentiles. Nor do the Jews like the idea that God's Promises were moved to Christ's Church.
In reality, all those views have some justifications along with non-Biblical doctrine, i.e., Replacement Theology has some truths in it while also some untruths, along with failure to address many things in all of God's Word. That's a sign of a tether, like I said before. It's how the false prophets can easily add 'bread fragments' onto the five loaves so one never really comes to the Truth of God's Word about it.
To truly understand the differences between the seed of Israel, the nation called Israel in the middleast today, and the Body of Christ's Church, all of God's Word must be studied, not just the New Testament Books only. And that means a very healthy dose of His Word about the concept of His election, regarding His election both according to seed and according to His Grace.
Another important subject in His Word that must first be grasped too is that of God's Birthright promise, what all it contains, when He first gave it, through whom it continued, and where it only is revealed upon today.
And still another subject that must be understood is how and when God fulfilled the prophecy to Ephraim's seed becoming "a multitude of nations" per Gen.48, because all history has ever known is the one nation of Israel, and not a multitude of them which that prophecy specifically points to.
And yet another subject, the topic of the ten lost tribes of the "house of Israel", the Bible prophecies involving what God would do through them.
Those above subjects are by no means a complete list involving this topic either. And I don't know of any Church that covers them, but instead I note how most Churches tend to shy away from those Bible topics because of not wanting to offend Gentile or Jewish believers in Christ's Body, because a full wine covering of it will offend some from both groups.
