'Necessary' in the Bible

But as for me, brothers, if I am still preaching circumcision [as I had done before I met Christ; and as some accuse me of doing now, as necessary for salvation], why am I still being persecuted [by Jews]? In that case the stumbling block of the cross [to unbelieving Jews] has been abolished.

From now on let no one trouble me [by making it necessary for me to justify my authority as an apostle, and the absolute truth of the gospel], for I bear on my body the branding-marks of Jesus [the wounds, scars, and other outward evidence of persecutions—these testify to His ownership of me].