Treasury of Scripture Knowledge
For [certain] false brothers, who were secretly brought in to observe us practicing our liberty in Christ Jesus [i.e., by not having Titus circumcised], attempted to place us [back] under the bondage [of Mosaic law keeping].
But now that you have come to know God [as your Father], or rather, to be known by Him [as His children], how can you turn back again to the weak, cheap, elementary teachings [of the law of Moses], to which you [seem to] desire to become enslaved?
But, brothers, if I were still preaching [that a person had] to be circumcised, why am I being persecuted? [Note: Paul's argument seems to be "I must not be preaching circumcision since I am being persecuted by those who believe in it"]. [If I preached that a person had to be circumcised] then my preaching that Christ died on the cross would not be such an offense [to those who believe in it].
For if your brother is hurt [spiritually] by [your eating a certain] food, you are no longer acting lovingly [toward him]. Do not destroy [spiritually] the person Christ died for by what you eat.
1 Corinthians 8:11
So, this weak brother, for whose sake Christ died, becomes [spiritually] destroyed, [and all] because of your "knowledge" [i.e., you know that such eating is harmless, but your weak brother does not know this, so he is led into sin by your unloving example].