I think that is a sophisticated answer.
To "hang on to what is good" is certainly good, but why hang on to - and defend - the bad also?
If religions are to be ranked according to the lowest number of flaws, then the best religion simply has to have one less flaw than the others to feel settled - even though this is to negate the notion of "carefully examining everything and hanging on to what is good". But religion is not the issue: the issue is the God we worship, and perpetuated debate as to which religion is the least worst is a very earthly distraction from that.
There is an example in the LDS - they added some text to the end of the book of Genesis to prophesy the advent of Joseph Smith. LDS explain this in various ways, such as
"God told him to do it"
which is difficult to disprove, and with that the - quite disgraceful - flaw is perpetuated. Other religions do the same... The simple way out of this is to practice 1st Thessalonians 5 in loyalty to God rather than church, and especially with regard to the churches which say that to follow them is to follow God.