Because the political left does not believe in objective wrong or right, it will eventually end up with a bunch of civil infighting and chaos. A political party that does not believe in objective morals or principles will implode due to dysfunction.

Conservatives will win IF, and only IF, they stick to their core principles and values: God, country, freedom, morality, and principles. It's as simple as that.

Conservatives already have a massive advantage over liberals. The only thing that hurts conservatives is when conservative leaders give ground to liberals and try to pander to the loony liberal crowd. You can't get rid of evil by pandering to evil or giving ground to evil. You have to stand firm against evil & amorality.