by hindering us from speaking to the Gentiles that they might be saved—so as always to fill up the measure of their sins. But wrath has come upon them at last! (1 Thessalonians 2:16 - ESV)
Continued clarification as to how the Jews of Jerusalem perscuted the church, killed Jesus, displeased God, and ultimately were opposing all of mankind: They hindered the Gospel. Hindering the speaking of the Gospel is opposition to all of mankind.
This verse ends on a challenging statement. Paul mentions that they are filling up the measure of their sins. and that wrath has come. There are many views on this, and commentators do not agree on the meaning, but there is a consensus that in some way it echoes Old Testament statements like the ones referring to the sin of the Amorites not being complete... (Genesis 15:16) The wrath that has come upon them is most likely referring to the fact that those who do not believe will experience the fullness of God's wrath.