Where in the Padma Purana are the following verses located?
Na śūdrā bhagavad-bhaktās te tu bhāgavatā matāḥ
Sarva-varṇeṣu te śūdrā ye na bhaktā janārdane
A devotee should never be considered a śūdra. All the devotees of the Supreme Personality of Godhead should be recognized as bhāgavatas. If one is not a devotee of Lord Kṛṣṇa, however, even if born in a brāhmaṇa, kṣatriya or vaiśya family, he should be considered as a śūdra.
Sva-pākam iva nekṣeta loke vipram avaiṣṇavam
vaiṣṇavo varṇo-bāhyo ’pi punāti bhuvana-trayam
If a person born in a brāhmaṇa family is not a vaiṣṇava, a non-devotee, one should not see his face, exactly as one should not look upon the face of a caṇḍāla, or dog-eater. However, a Vaiṣṇava found in varṇas other than brāhmaṇa can purify all the three worlds.
śūdraṁ vā bhagavad-bhaktaṁ niṣādaṁ śva-pacaṁ tathā vīkṣate
jāti-sāmānyāt sa yāti narakaṁ dhruvam
One who considers a devotee of the Supreme Personality of Godhead who was born in a family of śūdras, niṣādas or caṇḍālas to belong to that particular caste certainly goes to hell.
Source: Purport section of this website.