In the gospel to Israel, fruit is required as evidence of belief. In the gospel of the transcendent grace of God (Paul's gospel; the gospel to the nations), fruit will naturally follow belief but is not required as evidence of it. Note the difference between fruit being REQUIRED and fruit naturally FOLLOWING
belief.
The Israel gospel speaks of fruit as the offspring of a believer. Paul, however, speaks of it as the offspring of the holy spirit (Galatians 5:22) WITHIN a believer (1 Corinthians 3:16).