Non-religious son

Of course. I meant to ask about the subject as a whole in this way.
For example, should the father push him to get married or on the other hand even try to prevent him from it from a halakhic perspective?
In other words, the question is whether the marriage itself is a mitzvah and a positive thing even if it is clear that the problematic halakhic implications it will bring, or not.

This is a broader question with several aspects. Like whether from a Torah perspective, life in itself, even without observing mitzvahs, is positive and observing mitzvahs (of and keep yourselves and not commit suicide, etc.) but that they have the disadvantages of observing private mitzvahs, or whether halakhically if a person does not observe mitzvahs and commits offenses whose law is established in principle, it is better that he does not live. If there was a court, etc., it would already happen, but essentially it is like this.
I would very much appreciate an answer with halakhic sources, of course, and thank you for all your work.

Even if there was a court, etc., it wouldn't have happened. It's rare for a Sanhedrin to execute someone and not for things like this. And you know what they say about it in a situation like this. Go out and learn.

The question of whether life is a means to a commandment or not was discussed in column 421. There I explained that in my opinion life is a value in itself.
I think that a distinction should be made here between a gay man whose marriage is necessarily forbidden, and in which case I would not push him to marry (although I do not object, because it is outright rape), and the marriage of a secular child, in which case there are not necessarily any prohibitions. He will decide whether to conduct it lawfully or not. It is like the obligation to save the life of a secular person, even if the reason for postponing Shabbat is “to violate one Shabbat for him so that he will keep many Shabbats”, and he will not keep it. There too, the obligation is to save his life and allow him to keep many Shabbats. What he does with it is his decision. It is the law here.
What is more, marriage has a role in a person's life regardless of whether he conducts it lawfully or not. A marital unit is important socially and also for the couple themselves.
I don't provide sources for questions that don't have clear sources, and certainly not binding sources. In situations like this, everyone does with the sources whatever they want. I wrote my opinion, so now you have at least one source.

Here is a line of thought that comes to mind:

The father's attitude depends on the alternative. If the son commits more offenses in this world because of his marriage – then this is a sad step. If in the meantime he commits the same offenses, then this is a happy step, because if he does not have the next world, at least he will have this world...

And what is this about the wicked being lost? And the purpose of hatred is hatred?

I assume that he is not the kind of wicked person who is commanded to hate him and rejoice in his death, because of the spirit of heresy in the world and the religious situation in the Jewish people, etc. (as explained in the Ramban, Maharil, and Hazon Ish). And yet, it is possible that he lost his spiritual world, at least a central part of it.

Thanks Rabbi for the answer.
The source you cited from ”He profaned one Sabbath” is also certainly valid for the ”reasonable person” who would not dare to say that this law does not apply to a secular person (and on the question of marriage he would be satisfied).
Although each source will be interpreted by everyone according to what he thinks, I would still appreciate it if you could still throw a few sources here and there. Also regarding the issue of whether the likely reality that will occur in the future is included in weighing the parties to the current observance/non-observance of a mitzvah