You’d have been better off just quoting Copleston, as his quote was the best part of that dog’s breakfast of a response. The questioner measured God with the measure that Christians claim for him and found him wanting. It is disingenuous to try and avoid that failure by trying to switch to another measure mid-question. While it is true that there is no objective morality, Christianity makes the claim for both a God and an objective morality, making it perfectly valid to compare both in assessing the internal consistency of the Christian claim. If perfect justice is claimed for God and if a person’s acceptance of the obligation of an objective morality based on God requires knowledge of that God, than providing a person to be judged with less than sufficient information to clearly prove God’s existence (and thus create responsibility to the objective moral standard) is an unjust act according to the very standard of justice being claimed. So God fails to act justly by the very standard of justice he is claimed to uphold. While this doesn’t disprove the possibility of “a” God, it does take Yahweh off the list of contenders, at least according to the traditional Christian explanation.