If you want a good plant, start with good soil and good seeds. If these are not in place all sorts of things could happen. I once unknowingly used dirt filled with wild morning glory seeds. As you might well imagine, about the only thing grown was wild morning glories. Or thinking you’re planting cosmos and finding marigolds. There’s a shocker.
In a similar way we are encouraged to harvest all of our theology, or catechesis, our preaching from the seeds of Scripture planted firmly in Sacred Tradition. Because it is the Word of God, it constantly leads us to truth and deeper understanding of our God. (Personal note) When one substitutes or dismisses the Word or takes the Word but dismisses its Tradition, all kinds of strange and new (compared with the 2,000 year old understanding of the faith) start popping up. One need not look very far to see examples of this. Step off of the Catholic front lawn and you will find people teaching just about anything you might want to hear in the name of Christianity.