The Epistle to the Hebrews, the authorship of which has been long debated, urges the Hebrew Christian community not to fall back into Judaism.

Hebrews 10

10:29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?