Christian liberty is an interesting concept. It creates a lot of suspicion whenever it is mentioned. It seems clear that Paul teaches that Christians have the liberty to have differences with each other on non essential issues.
Why does such a concept face such strong resistance?
The reality is that Christian liberty faces resistance because there are many who wish to abuse it. For example Christian liberty turns into sexual liberty - clearly this is an abuse of the concept.
How can a person maintain the concept of Christian Liberty without endangering oneself to grave error? I think it is simply the we must always seek to understand and learn and sit under the teaching of the bible.
You will always see two sorts of impulses among "Christians." The one impulse is to sit under the teaching of scripture. The other impulse is to stand over the scriptures and figure out what is actually true in the scriptures.
It seems pretty clear which impulse is correct. If Jesus is who he says he is and has done what he has claimed to have done how can you stand over his teaching.
It is a very interesting state that many people do not reject the existance of God and yet they wish to tell God he is wrong about issues.
It is difficult to understand the impulse it seems to verge nearly on the absurd to say that an all powerful and all knowing God exists and I will tell him he is mistaken on life issues.