Can Buddhist Practitioners Employ Heterodox Teachings?

The so-called non-Buddhist doctrines refer to teachings that do not pertain to the Tathagatagarbha, doctrines expounded apart from the mind of Tathagatagarbha, which are called non-Buddhist doctrines. Many non-Buddhist doctrines are greatly beneficial to Buddhist practitioners; therefore, one should not reject useful non-Buddhist methods. For instance, doctors treating patients with medical methods is also a non-Buddhist approach. Can we abandon non-Buddhist methods and rely solely on the Tathagatagarbha doctrine to resolve all matters? Clearly, we cannot. Non-Buddhists eat, and we must also eat; non-Buddhists live on Earth, and we cannot leave Earth either; non-Buddhists breathe air, and we also breathe the same air. Since beginningless kalpas, we have never been separated from non-Buddhist doctrines. Even after learning Buddhism, we must still practice methods identical to those of non-Buddhists; this is necessary. Apart from lacking the Tathagatagarbha doctrine and the doctrine of the non-self in the five aggregates, non-Buddhists possess all other methods, which we too must fully embrace. For example, the renunciation mind, liberation mind, and meditative concentration found in non-Buddhist traditions, along with various methods for addressing physical ailments, are all highly worthy of our study. As long as they are useful to us, we should employ them. In reality, all non-Buddhist doctrines are essentially the Tathagatagarbha doctrine. Even when doctors heal patients, it is ultimately the Tathagatagarbha that effects the cure; fundamentally, it remains the Tathagatagarbha doctrine. No person or doctrine can exist apart from the Tathagatagarbha; all are born from the Tathagatagarbha, and in essence, all are the Tathagatagarbha.