How do we know the promise of the new covenant is true?

In the new covenant, as foretold by the prophet Jeremiah, God promises to put His laws in the minds and hearts of His people (Jeremiah 31:33). This promise is fulfilled in Christ, who enables believers to truly know and understand Him. The evidence of this transformation is seen in the lives of those who have been born again, marked by a desire to worship God in spirit and truth. The indwelling Holy Spirit is a guarantee of this new covenant, assuring believers of their salvation and their continuing transformation into the image of Christ.