There are a number of tenets central to contemporary secular humanism (for a taste of what such humanists in NI believe see their website: http://humanistni.org/what-is-humanism/). What appear to generate a lot of their beliefs are: (i) the focus on the human being and (ii) secularism. It is important to bear these in mind, especially (ii), since humanism itself is not an essentially secular philosophy insofar many religious thinkers of the Western tradition have given very focused attention to the human being even going so far, as Aquinas does, in holding that the human being is the most significant of all creatures since it involves all aspects of both the material and the spiritual thereby uniting the two. Not only that, renaissance humanism was peppered by many religious thinkers, most notably St Thomas More. Hence what typically characterises contemporary humanism is its rejection of religion.
Setting aside the rejection of religion for a moment, there are many beliefs of secular humanism that are shared with religious thinkers of the past. So for instance the focus on a common humanity that unites all human beings; the emphasis on critical reason for our knowledge of the world, and the defeasibility of the deliverances of such reason; the ability to know what the good life is and the virtues independent of revelation; the worth and dignity of every individual and the need to live a full and happy life.
All of these positions and others have been adopted by significant religious thinkers in the past. It is worth considering the outlook of the representative religious thinkers I have in mind, thinkers like Avicenna (a Muslim), Moses Maimonides (a Jew), and Aquinas (a Catholic), not to mention the pagan thinkers Plato and Aristotle. The outlook that unites all of these people is that rationality is the specific difference of what it is to be human, so that in order to live a fully human life one must live a rational life. In order to live a rational life, one must do what one can to perfect one’s rational abilities, and this pertains to (i) knowing the truth and (ii) acting with respect to the truth. In order to know the truth, one must engage one’s critical reason and in order to act in respect of the truth one must know what the good of human life is and act accordingly. Hence these thinkers can affirm our common humanity, the emphasis on critical reason for knowledge of the world, the process of reasoning, knowledge of the good life independent of revelation, and the dignity of all human beings (though the latter is a position more closely focussed on by Catholic thinkers given their views of the person stemming from the theology of the Trinity).
Clearly then these thinkers did not see any inconsistency between their religious beliefs and the views they hold in common with what are now secular humanists. Part of the reason why they did not see any inconsistency is because their outlook entailed that the existence of God, knowledge of His nature, and the reasonableness of claims made in revelation about God can all be known by means of natural reason (Plato and Aristotle of course did not deal with the latter claim). Thus, these religious thinkers saw the engagement of their critical reason as something that was capable of being integrated with their religious outlook and not inimical thereto.
Now secular humanists may wish to dispute the details of the arguments for God’s existence, the philosophical reasoning by which God’s nature can be known, or the reasonableness of claims made in revelation. If our humanist brethren are correct in this regard (though I don’t think they are, see my book Aquinas’s Way to God: The Proof in De Ente et Essentia, Oxford University Press, 2015), then all that establishes is that in their view such claims are false, not that they are irrational. This is because the religious claims put forth by the aforementioned thinkers are defended by means of the same philosophical framework and commitment to the same philosophical ideals with which secular humanists would wish to reject them. Accordingly, there is no division between critical reason and religious belief, and when it comes down to the claims of religious believers such as the existence of God, His nature, and the reasonableness of the claims of revelation, one simply has to read the argumentation of the religious thinker in question in order to ascertain whether or not the position being put forth is true or false. Thus, one needs to read the works of Plato, the Metaphysics of Aristotle (especially his demonstration of God in Book 12), the Metaphysics of Avicenna, the Guide for the Perplexed of Maimonides, the Summa Theologiae of Thomas Aquinas and many others in order to ascertain the truth value of the religious claims made therein.
But this sort of high level and detailed engagement is not something that one sees with regard to secular humanists, since to do so they would have to accept the legitimacy of philosophical reasoning in order to refute such thinkers; yet it is the same framework by which these thinkers establish their religious claims, in which case the claims themselves are not opposed to the rationalist frame of mind of secular humanists. Indeed, I have worked with many atheist colleagues and read their very fine contributions to high level international philosophical journals, and such colleagues accept that religious believers do take the task of critical reason very seriously, and indeed they engage with them in the same journals and publications – they simply disagree that the argumentation is conclusive (as do the religious with respect to the atheist argumentation). But at no point are the rational credentials or the commitment to critical reason in doubt – we are all agreed in our commitment to critical reason, we disagree in what can be established from it.
With that in mind then, the religious claims of the thinkers mentioned above are made in light of critical reason and not independently of it. Given the latter, there are publicly accessible reasons for coming to believe a religious claim (or not). And if there are publicly accessible reasons for accepting a religious claim (or not) that claim has a place in public discourse.
Dr Gaven Kerr