To attain liberation from the suffering of samsara, one must succeed in realization of emptiness being the true nature of all phenomena,regardless of its apparent difficulty. One needs to overcome this last hurdle, renunciation and bodhicitta being the first two, before going further on the path to liberation.Once the first two are fully generated, realizing emptiness will come next. Without the latter, liberation would still be beyond reach even with renunciation and bodhicitta completely aroused. There is just no way to get around this. So ultimately, one must attain realization that all phenomena are emptiness.
~ Depicted from THE RIGHT VIEW - The Three Supreme Methods—the ultimate methods of cultivating virtue and training the mind