“First, to map out the boundaries within which all discussion must go on, I take it for certain that the physical satisfaction of homosexual desires is sin. This leaves the homosexual no worse off that any normal person who is, for whatever reason, prevented from marrying. Second our speculations on the cause of the abnormality are not what matters and we must be content with ignorance. The disciples were not told why (in terms of efficient cause) the man was born blind (John 9:1-3): only the final cause, that the works of God should be made manifest in him.
This suggests that in homosexuality, as in every other tribulation, those works can be made manifest: i.e. that every disability conceals a vocation, if only we find it, which would “turn the necessity to glorious gain.” Of course, the first step must be to accept any privations which, if so disabled, we can’t lawfully get. The homosexual has to accept sexual abstinence just as the poor man has to forgo otherwise lawful pleasures because he would be unjust to his wife and children if he took them. That is merely a negative condition.
What should the positive life of the homosexual be? I wish I had a letter which a pious male homosexual, now dead, once wrote to me – but of course it was the sort of letter one takes care to destroy. He believed that his necessity could be turned to spiritual gain: that there were certain kinds of sympathy and understanding, a certain social role which mere men and mere women could not give. But it is all horribly vague – too long ago. Perhaps any homosexual who humbly accepts his cross and puts himself under Divine guidance will, however, be shown the way. I am sure that any attempt to evade it (e.g., by mock- or quasi-marriage with a member of one’s own sex even if this does not lead to any carnal act) is the wrong way.”
CS Lewis in Walter Hooper (Ed)., The Collected Letters of CS Lewis Vol III, p.471.