One of the bedrock principles of being married in the Catholic
Church is that you understand that all your children will be raised
Catholic. This has always applied to both spouses, even in the
exceptional case when one of them is not Catholic, for, traditionally,
when a Catholic wants to marry a non-Catholic the Church requires
they both promise to raise their children as Catholics, otherwise the
mixed marriage would not be allowed.
Furthermore, the parents are both obliged to not delay
(unnecessarily) the baptism of their children. But what could
constitute a valid reason to delay it? Certainly being able to have a
nice Baptism Party is not a valid reason. Nor is it a valid reason to
wait until his uncle Fred is able to make the trip from overseas, like
next year. Things like that.
The obligation to baptize your new baby is a serious obligation and
deliberately not doing it qualifies as a mortal sin, of course, one
needs to know that it is a mortal sin and do it anyway, but how do
you get to be married in the Church without knowing it? Well, this is
going on these days. Some so-called Catholic priests tell the faithful
very strange and ambiguous things, that they often misunderstand
and do not come away from that knowing what the Church teaches,
and in that case the priest is responsible for the errors that result.
The errors can be by omission, in this case, not knowing this
teaching is a lack of knowledge. Now, if you do not "know it"
because you have CHOSEN to not believe it, then your choice to
disbelieve what the Church teaches is a serious sin that affects a lot
of other sins. It is really a serious sin all on its own, that must be
confessed!!