Notice what it does not say: it does not say he chose us to be in him. Calvinists like to rewrite the Bible to fit their agenda. The spiritual blessing in the heavenly places in v3 is the context. These blessing were placed in Christ. God would choose to give these heavenly blessings to those in him, in Christ. The word "according" at the beginning of v4 put the context back to the previous verse.
3 Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ:
4 According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love:
3 Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with all spiritual blessings in heavenly places in Christ:
4 According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love:
Also "trying to rewrite Bible to fit the agenda" is a problem of all Christians, not just of one specific group, be just.