John Stott has some wise words about Christian political influence:-
Although it is hardly the responsibility of a church or denomination as such to engage in direct political action, yet Christian individuals and Christian groups should be doing so, and should be encouraged from the pulpit to do so. For Christian should aovid the two opposite mistakes of laissez faire (making no Christian contribution to the nation’s political well-being) and imposition (trying to force a minority view on an unwilling majority, as with the American liquor laws during the period of Prohibition). Instead, we remember that democracy means government with the consent of the governed, that “consent” means majority public opinion, and that public opinion is a volatile thing, which is open to Christian influence. Pessimists will respond that human nature is depraved (which it is), that Utopia is unattainable (which it is), and that socio-political activity is therefore a waste of time (which it is not). It is really absurd to say that social amelioration by Christian influence is impossible. For the historical record demonstrates the contrary. Wherever the Christian gospel has gone and triumphed, it has brought in its wake a new concern for education, a new willingness to listen to dissidents, new standards of impartiality in the administration of justice, a new stewardship of the natural environment, new attitudes to marriage and sex, a new respect for women and children, and a new compassionate resolve to relieve the poor, heal the sick, rehabilitate prisoners, and care for the aged and dying. Moreover, these new values become expressed, as Christian influence grows, not only in philanthropic enterprise but also in humane legislation.
Stott, I believe in preaching, 166