I believe I can disprove it. But I don't expect Christians to agree with me. We're left at interpretation of things which people disagree on.
Take for example the entire structure of the new covenant Christians claim. Where is that from?
Jeremiah 31
31 “Behold, the days are coming, declares the Lord, when I will make a new covenant with the house of Israel and the house of Judah, 32 not like the covenant that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt, my covenant that they broke, though I was their husband, declares the Lord.
Ok, so that's where the concept comes from. But what comes after?
33 For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people.
Well, that makes it seem like any concept of the Jewish people not following HaShem is foreign to the text. We will have the Torah written on our hearts and we will be His people. What next?
34 And no longer shall each one teach his neighbor and each his brother, saying, ‘Know the Lord,’ for they shall all know me, from the least of them to the greatest, declares the Lord. For I will forgive their iniquity, and I will remember their sin no more.”
Now I look at that and go "Oh, well that clearly hasn't happened, so there can't be this new covenant yet." Christians will either tell me that it is happening slowly over time or tell me that it will happen.
Here we are at interpretation. Who's correct? Who has the absolute truth? In my opinion, this right here disproves that a new covenant exists at this time. To a Christian, the New Testament (which means new covenant) states that it exists so it does.