The same way that churches allow politics from the left from their pulpits and it doesn't affect their tax exempt status.
What you can do in a church is say that abortion or war or sex outside of marriage are against the rules of this church and this is the stand of politicians on various issues (a voter guide that says candidate Jones is for reproductive rights (abortion), but candidate Smith is against abortion or reproductive rights. But such a voter guide might have the candidates stand on gun rights, defense spending, social programs, etc., as well.
Additionally, the churches are not directly getting tax dollars for work that they might promote a candidate support.
In other words, if I advocate in my organization that people elect candidate Jones, and then candidate Jones votes for tax dollars for my organization to operate abortion clinics, under the same name and affiliation, is this not a quid pro quo where both the political candidate and the organization are working hand in hand with really no distinguishable lines.
I would understand and not consider it fraud if the organization that was politically actions was called the Reproductive Rights League and the abortion clinics were called Charitable Women's Health Clinics.
Then there would be no tie in directly between the two organizations - in name or in organization.
But the head of Planned Parenthood Federation has control over all activities - abortion clinics and political action.
So where has the line been drawn?