The fact of the matter is that passage in context, 1 Corinthians 1:26-31, shows, without a shadow of doubt that it is God who chose us. This had nothing whatsoever to do with our choosing, deciding, believing, repenting, or as he believes, gaining grace for humbling ones self (James 4:6 ripped out of context and abused). The text there is written to believers and isn't about God favoring one over another as his choice meats doctrine corrupts the teaching.
The passage in 1 Corinthians has everything to do with God did it all, not us, and there is no reason for man to boast, verse 32, but only in God and what He has done. The Corinthians knew this truth, this milk of doctrine. Many today reject it because they were never taught the truth when they professed faith. Instead they were told that they decided, accepted, chose, and were congratulated for what they did. Biblical election and predestination were mitigated out of fear of the truth of God being God.
The fact remains that God alone elects to salvation whom He willed to save, choosing them in Christ prior to creation; Ephesians 1:4. Only those who were born of God, regenerated; Ephesians 2:5; John 1:13 receive Him. God caused all of that, not "choosing." Soli Deo Gloria!