CEF's clients are those whose parents are lost, who have never clued their dependents on sin, the Savior, and salvation.
I am acquainted with adults who were attracted by, and became saved, because CEF gave them the same Good News given to their children. And this includes adult parents raised up in and attending Methodist, Presbyterian, Lutheran, and Catholic cultures, who though superficially religious, had no idea they were spiritually lost.
For CEF to approach my grandchildren or anyone else's children, I will tell them, "Go to it!" and give them my support and my encouragement.
They are obeying the Lord's ordinance of the Great Commission.
For your grandchildren, you are screening and making a positive decision, which is fine with me. For "anyone else's children"... for example mine, you are making that decision for me, which I object to. Ask me first.