The point of this passage is to make clear that, no matter how much one may aspire to the Buddha way by calling upon the name of Amida Buddha, or by embracing the teachings of the Zen school—relying on the sutras of the Flower Garland, Agama, Correct and Equal, and Wisdom periods preached by the Buddha during the previous forty years and more—one will never succeed in attaining supreme enlightenment, even though a countless, limitless, inconceivable number of asamkhya kalpas should pass.
And this is not the only passage of this type. The “Expedient Means” chapter of the Lotus Sutra states, “The World-Honored One has long expounded his doctrines and now must reveal the truth.” It also says, “[In the Buddha lands of the ten directions] there is only the Law of the one vehicle, there are not two, there are not three.” These passages mean that only this [Lotus] sutra represents the truth.[/u]
And here is the explanation:
"And he says to them, � All of you should take no pleasure in dwelling in the burning house of the Three Realms. Do not lust after vulgar and evil forms, sounds, smells, tastes and tangible objects. If you attach to them greedily and give rise to love for them you will be burnt. You should quickly escape the Three Realms and obtain the Three Vehicles; the Sound Hearer, Pratyeka Buddha, and Buddha Vehicles. I now give my pledge for this and it shall never be proved false. You need only diligently and vigorously cultivate. The Thus Come One using these expedient means leads all creatures.
In other words, if you don't abandon evil doings such killing, lust, stealing, lieing, and other forms of attachments, you will not succeed whether you practice Pure Land, Chan, or any other forms of meditation. To explain this further, you need to at least cultivate 10 virtuous acts that are opposite to 10 evil acts by karma of body, speech, and mind...body does not kill, steal, sexual misconducts, speech, no lieing, no idle speech, speech that create conflicts, etc, mind-3 poisons.
So those are the basic pre-requisites. Then meditation whether by Chan, Pure Land, or any other form is just the boat to enlightenment.
Naturally when start working on the pre-requisites; we will be more at peace. So that’s why I asked many times on this forum what it means to meditate. If we truly want to achieve peace in our lives and not just a relaxation session, we have to work on those pre-requisites. And meditation will give great results when we also work on pre-requisites at the same time.
In short, the karma of body, speech, and mind is like wood, to cut the fire we have to withdraw this wood.