In Catholicism is it a serious sin to make major decisions as if you don't believe in Catholicism?

In Catholicism is it a serious sin to make major decisions as if you don't believe in Catholicism? >"844. Negative doubt is the state of mind in which one remains suspended between the truth contained in an article of faith and its opposite, without forming any positive judgment either of assent to or dissent from the article, or its certainty or uncertainty >(a) If this suspension of decision results from a wrong motive of the will, which directs one not to give assent on the plea that the intellect, while not judging, offers such formidable difficulties that deception is possible, then it seems that the doubter is guilty of implicit heresy, or at least puts himself in the immediate danger of heresy. >(b) If this suspension of judgment results from some other motive of the will (e.g. from the wish to give attention here and now to other matters), the guilt of heresy is not incurred, for no positive judgment is formed. Neither does it seem, apart from the danger of consent to positive doubt or from the obligation of an affirmative precept of faith then and there (see 925), that any serious sin in matters of faith is committed by such a suspension of judgment. Examples: Titus, being scandalized by the sinful conduct of certain Catholics, is tempted to doubt the divinity of the Church. He does not yield to the temptation by deciding that the divinity of the Church is really doubtful, but the difficulty has so impressed him that he decides to hold his judgment in abeyance. It seems that there is here an implicit judgment (i.e., one contained in the motive of the doubt) in favor of the uncertainty of the divinity of the Church. Balbus has the same difficulty as Titus, and it prevents him from eliciting an act of faith on various occasions. But the reason for this is that an urgent business matter comes up and he turns his attention to it, or that he does not wish at the time to weary his brain by considering such an important question as that of faith, or that he thinks he can conquer a temptation more easily by diverting his thoughts to other subjects (see 257), or that he puts off till a more favorable moment the rejection of the difficulty. In these cases there is not heretical doubt, since Balbus forms no positive judgment, even implicitly, but there may be a sin against faith. Thus, Balbus would sin seriously if his suspension of assent should place him in immediate danger of positive doubt; he would sin venially, if that suspension be due to some slight carelessness." (McHugh & Callan, *Moral Theology* Vol. I) For example, suppose Bob is dating a Catholic woman and would like to marry her as soon as possible. However, he has some doubts about whether Catholicism is true or not and whether he will ultimately remain Catholic although he continues to practice Catholicism in the mean time. For this reason he is delaying getting married. What will happen to Bob if he dies suddenly? Sure he is theoretically a Catholic in good standing, but he is living as if he doesn't believe in it.