"Do you think homosexuality is criminal?" is a meaningless question to ask. It does not matter what anyone thinks homosexuality is not a criminal activity: that is a matter of law, of fact.
Has Tim Farron ever made a secret of his christian views? If not, then was his attitude to homosexuality a matter raised during his party leadership campaign? Again, if not, then why not?
What is it about the Abrahamic religions that causes them to be so obsessed with matters of sex and sexuality? My guess is that private and personal behaviour can be used to generate guilt and shame .... and hence control.
I don't find it particularly puzzling why religions from many centuries ago have moral rules about sexual behaviour. My impression is that religions developed to regulate behaviour - that's one of the main reasons they were popular as they provided a form of social control. Social control in areas such as monogamy, marriage and sex outside marriage served a useful purpose once people started bequeathing property.
Also the moral rules presumably were to try to regulate and stabalise society as humans can get violent or somewhat emotionally destructive when their partners are sexually unfaithful. Presumably regulations around who can have sex with whom came about in societies where sex was a big deal emotionally for humans, as well as the rules being a way of trying to control the spread of sexual diseases that would have created fertility issues. A society trying to survive with no welfare state or free health service would have produced rules to limit wastage of resources, especially where they needed men to serve as soldiers to conquer land or defend land and didn't want romantic or sexual complications to interfere with troop discipline.
I agree that Farron should have told the truth about his personal views on sin. He said in an interview that “I take the view that, as a political leader though, my job is not to pontificate on theological matters.”
As an MP he can be judged on his voting record and if people disagreed with the way he voted, then quite rightly he would have lost their political support.