"When a man makes a moral choice two things are involved.  One is the act of choosing.  The other is the various feelings, impulses and so on which his psychological outfit presents him with, and which are the raw materials of his choice.  Now this raw material may be of two kinds.  Either it may be what we would call normal: it may consist of the sort of feelings that are common to all men.  Or else it may consist of quite unnatural feelings due to things that have gone wrong in his subconsious.  Thus fear of things that are really dangerous would be an example of the first kind: an irrational fear of cats or spiders would be an example of the second kind.  The desire of a man for a woman would be of the first kind: the perverted desire of a man for a man would be the second.  Now what psychoanalysis undertakes to do is to remove the abnormal feelings, that is, to give the man better raw material for his acts of choice; morality is concerned with the acts of choice themselves."  Mere Christianity

Personally, I find what Lewis has to say about the relationship between morality and psychoanalysis to be very astute.  To distinguish between the morality of our choices and the feelings presented by our "psychological outfit" is essential.

There are many people today who would not agree with Lewis's definition of normality--especially when it comes to sexuality.  The increasingly widespread assumption today is that if certain desires, namely homosexual ones, appear very early in life, then those desires must be normal for that person, due to their "nature" more than their "nurture", in short, those desires must be God-given.  However, this assumption does not take into account that there is something catastrophic which has taken place between God's original creation and the present moment--namely the Fall.  According to traditional Christian theology the Fall of humanity into sin has affected the nature of all human beings ever since.  With regard to homosexuality the clear teaching of Genesis 1 and 2 is that God originally created a man and a woman to have a sexual relationship with one another, not a man and a man or a woman and a woman.  However, since the Fall not all human beings have this normal, original, appropriate sexual desire for the opposite sex.

So where does this traditional Christian teaching leave the person who has homosexual desires?  According to Lewis, and all Christian teaching up until very recently, the person with homosexual desires who wants to obey God has two options:

1. Pray that God would change their desires so that they might pursue marriage with someone of the opposite sex.  (This is where appropriate counseling from a counselor who holds to the traditional Christian view might be of assistance.)
2. Pursue a life of celibacy.

Whichever option is pursued it will require the help of the Holy Spirit and the Scripture clearly indicates that change is possible.  The Apostle Paul says,

Neither the sexually immoral nor idolaters nor adulterers nor male prostitues nor homosexual offenders nor thieves nor the greedy nor drunkards nor slanderers nor swindlers will inherit the kingdom of God.  And that is what some of you were.  But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God  (1 Corinthians 6:9-11).

Does this mean that the person with homosexual desires who is sanctified will never have those desires again, or never give into homosexual temptation again?  Not necessarily.  But as Lewis says elsewhere, the important thing is not 100% success in this life, rather what is essential is the virtue of always trying again.

I know all about the despair of overcoming chronic temptations.  It is not serious, provided self-offended petulance, annoyance at breaking records, impatience etc. don't get the upper hand.  No amount of falls will really undo us if we keep on picking ourselves up each time.  We shall of course be very muddy and tattered children by the time we reach home.  But the bathrooms are all ready, the towels put out, and the clean clothes in the airing cupboard.  The only fatal thing is to lose one's temper and give it up.  It is when we notice the dirt that God is most present in us; it is the very sign of His presence. . . . (Letters of C. S. Lewis, 20 January 1942)

Dear God, you alone know the chronic temptations I am trying every day to overcome.  Grant to me the help of your Spirit, first to see reality, to see my temptations for what they are, and then give me the courage and strength to overcome them by your grace to your glory.  Thank you that when I fail you forgive and cleanse me afresh by the blood of Christ shed for my sin upon the cross.  When I do fail help me to confess the same to you and then get up, once again, to run the race you have set before me.  As I run, help me to remember that you are, at the same time, my Father cheering me on to the end of the race, my elder brother Jesus running the race beside me, and the Holy Spirit living within me to help me run.  Amen.