(Eph 1:4 [NET])
For he chose us in Christ before the foundation of the world that we may be holy and unblemished in his sight in love.

How did our state of being blessed with EVERY spiritual blessings come about?

This clause says three things:

1. God chose us for these blessings.

2. God chose us in Christ. This is very important given the content of the later chapters in the letter regarding the essential unity of Jews and Gentiles. There are no blessings that arrive to us from God apart from Christ.

3. God chose us before the foundation of the world. Our salvation was marked out before God said the first word of creation. Even though human beings were created last, they were thought of first.

The fact that we are in Christ provides the basis for the last part of the verse. IN CHRIST, we are holy and blameless in His sight. HIS sacrifice has been applied TO US, so that God no longer sees our sin, but Christ's righteousness!

Just as God intended from before the beginning.

Chris