As I explained earlier Steve, "the family" is a strong component of society. It is championed by the Pope and all Churches.
Homosexual "marriage" and" abortion on demand, both negatively affect society. Firstly by redefining the meaning of marriage to encompass relationships other than "one man one woman", which removes procreation and the construction of family out of the equation.
One man one woman may of course choose not to procreate, or be unable to do so, but that would be personal choice, not edict.
It also opens the door to other forms of relationship claiming validation by use of the institution.

Abortion on demand weakens society in that life once created can be disposed of in the manner of a useless commodity, to serve PERSONAL convenience.