Here's the reading, courtesy of Catholic.org:
25 Great crowds accompanied him on his way and he turned and spoke to them.26 'Anyone who comes to me without hating father, mother, wife, children, brothers, sisters, yes and his own life too, cannot be my disciple.27 No one who does not carry his cross and come after me can be my disciple.28 'And indeed, which of you here, intending to build a tower, would not first sit down and work out the cost to see if he had enough to complete it?29 Otherwise, if he laid the foundation and then found himself unable to finish the work, anyone who saw it would start making fun of him and saying,30 "Here is someone who started to build and was unable to finish."31 Or again, what king marching to war against another king would not first sit down and consider whether with ten thousand men he could stand up to the other who was advancing against him with twenty thousand?32 If not, then while the other king was still a long way off, he would send envoys to sue for peace.33 So in the same way, none of you can be my disciple without giving up all that he owns.
If I had to guess, I would say that Jesus is not commending, but rather contrasting, the actions of the king and the tower-builder with that of the good disciple. The king and the tower-builder are prudent, or, rather, should be prudent in their undertakings; the disciple, should not be. Most preachers I have heard do not interpret it this way, but I can see no other way to make sense of 'giving up everything' - even giving up cautious prudence. Now, I think he initially wishes to link the disciple with the king and the tower-builder by saying that everyone has to make a thoughtful examination of the cost of their undertakings - that it means sacrificing, perhaps, the esteem of family (hate of father), and wealth (all you own), and comfort (the cross). But unlike the king and the builder, the disciple's evaluation of the cost cannot determine whether or not he is to follow Christ, but simply to teach him what it means to follow so he does not make a rash decision from which he will later backtrack.
If my interpretation is incorrect, how then are we to link king, builder and disciple? If a closer analogy is implied, how then is the king suppose to give up everything he has? A king would be wise not to pick fights he cannot win. What choice does the disciple have? Can he choose not to follow Christ? Not really. That can't be considered prudent in the ultimate sense, can it? Jesus can't really be teaching people not to follow Him, like He is teaching that people shouldn't build towers they can't afford and begin wars they can't win.
The comparison is preceded by the admonition to carry one's cross. In this case I think we can say that that means taking on the truth of our circumstance: that follow Jesus will not be easy with family, wealth and comfort, and if you think it will be you are doomed to failure like this king and this builder.
The reading would have been much simpler had Jesus (or Luke) have included that simple phrase: don't be like the king who... or the builder who... because...
Now for the personal side of this. I want to focus on the hate of father and mother.
This is one of the costs of following Christ. It's not quite like the other two mentioned here because, unlike wealth and comfort, family is deserving of our love. Comfort and wealth are good, but they cannot be loved - they cannot receive our benefactions - like people can. Augustine simply said that things are to be used, people to be loved. Comfort is for health, for instance; it is not an end in itself. Money is for food, etc., not the meaning of life itself. People, however, are not to be loved so that I can feel good about myself, but because they are what they are and I am what I am. They are divine images, and if I can see them rightly I will admire them and want to do them good.
But these three things, nevertheless, Christ is telling me I have to come to grips with. He doesn't say give away family, as He does money. He says hate. He never tells us we should hate money. We can't love it so we can't hate it. There is not a single Catholic out there who hasn't heard that the Semitic word 'hate' is supposed to be interpreted as 'strongly prefer the other.' So, we should take Christ to be saying that we should strongly prefer God to father, mother, etc. The error, of course, would be to see an either/or situation here, as in the case of loving God or money (mammon). But He doesn't say family or God; He says God much more than family. And in another place He says love neighbor as self. So, it's not either/or, it's both a lot, but God more. The only limit to loving neighbor is not with my whole soul, mind and strength. Only God is to be loved that much. So, if your father says, worship a golden calf, you are not to listen at all. You are not to pretend that that is one choice among many, and that there is nothing wrong with that suggestion. No, it is a horrible suggestion, one to be despised.
In any case, it should never be an easy thing to hate father. How hard it is for children of alcoholics, for instance! Nor is it a sign of spiritual perfection to have transcended love of father. I know there is much apparently stated to the contrary in our spiritual literature. It is, as such, either poorly written, if so, or poorly interpreted, if not. If you get caught up in Thomas a Kempis or John of the Cross, etc., without a sound formation in theology, and these basic points I have been discussing, you might begin to believe that we should actually feel disdain or indifference for our families. No, it should bother you when your loved ones go off track, or suffer setbacks. Christians must be the best humans, not subhumans. Treating people like mere 'souls' to be saved is also disgusting. I don't like the name of that organization - One More Soul - for this reason (not to imply that any of its members views human life this way, but the name is, in my opinion, unhelpful). I don't have children out of the desire to give souls to God. Who thinks that way? Maybe we should name our next child Soul Number 6?!
In loving people we love real people with personalities and eccentricities, not abstractions. I think that there is a danger for people who 'take God seriously' to reduce people to mere abstractions. My father becomes this father who I have to hate compared to God, rather than the flesh-and-bones, lovely man, who is Stephen Kerr, Sr., or whatever the case may be.
Now, I have heard about this mother who has sent her young child far away to school who does not miss her child, believing that the absence of that feeling is a sign of spiritual perfection. It is one thing not to fall apart when adversity befalls us, quite another not to admit of human sensibility. At funerals we hear St. Paul say that we grieve but not like those without hope. The point is, we grieve. We are human. We love and therefore we miss.
If you are like me and mystified with this mother, do not be angry with her. Or, don't be angry for long. She means well. All I can do is point to Jesus who cried for Lazarus, the Blessed Mother who cried for Jesus, Monica who cried for her son, her son who cried for her. Augustine's Confessions is full of tears. In it he grappled with the spiritual value of human attachments. He was raised in a world dominated by Stoic philosophy, that saw these things as the antithesis of wisdom. By the time he wrote City of God, about a decade later, he had a much clearer view of the place of emotion in Christian life. Read Book 14 of that work. He went so far as to say that there would have been something quite inhuman about Christ were He not to have emotions! Not missing one's son, in other words, is a sign of spiritual sickness, not of holiness. And so we need to pray for those who are either in this state or who believe that we ought to become less hearty.
Hating father and mother is the preference the saint has who loves his neighbor so very terribly, but God just that much more. It has nothing to do with the person for whom this preference comes very easily, without cost, without wonder, without grief.
Love of God that is bought at the expense of neighbor is peculiar indeed. There is no reason why loving God more should lead one to loving neighbor less. Love is not a limited commodity.