The answer is along the lines of 'greater personal happiness than offered by the secular left'. For example by running a more efficient economy and education system (greater competition, dispensing with the system of racial and sexual preferences - aka. AA).
But there are two aspects of happiness - there is the personal happiness offered by a comfortable life in which one can express lifestyle preferences; and there is the second order happiness of knowing that other people are happy.
The secular right is not necessarily better at offering the first kind of happiness, in the sense that the left vote consists of interest groups to which resources are transferred from right voters (various greivance groups, plus the public sector workers, education and the media).
So that left voters would - both as individuals and as a group - mostly be made more miserable (at least in the short- to medium-term) by secular right policies.
This means that the happiness-based vote for the right entails a mathematical calculation of what makes most voters happier, or perhaps optimises happines for the most worthy voters; or perhaps (quite plausibly) what would maximize the happiness of the greatest number of worthy people in the long term - probably.
I think this is the basis of the secular right's appeal: that their policies would maximize the happiness of the greatest number of worthy people in the long term - probably.
On the other hand the secular right policies would reduce the happiness of many people in the long term, and of even more people in the short term.
And this reduction of happiness would happen certainly, not probably; and sooner rather than later.
So, the secular right attempts to transcend interest group politics in the interests of 'rational government'.
But it has no means for doing this.
This is, in a nutshell, why the secular right cannot get power in a democracy - except by deception; but then what got power would continue to deceive, and what got power certainly would not trascend interest group politics and implement the rational secular right program.