In love he predetermined us for the establishment as sons through Jesus Christ to himself, according to the good pleasure of his will
In love - In contrast to the wrath that the false teachers said would come upon the Gentiles during the Day of Destruction, Paul says that they were chosen in love.
- Ephesians 1:5
he predetermined us - False teachers were saying that Israel was God's chosen people and if God were to accept Gentiles, that would mean God had changed His will but Paul says that it was God's will from the beginning to include the Gentiles.
for the establishment as sons through Jesus Christ to himself - In the culture of the time only sons were able to receive an inheritance but Paul says that all those who follow Christ are reckoned as God's sons and will receive an inheritance.
according to the good pleasure of his will - It was not against God's will to choose the Gentiles as part of His people, nor was He angry to do it, but it was His will and He took pleasure in it.