[3:19] Lo, the religion (dīn) with God is submission (islām) (to the One God).
Religion (dīn): The [religion] that He is pleased with, and the one whose follower He has determined to reward, elevate and cause to meet favor, is submission (islām). Submission (islām) is sincerity (ikhlāṣ) and the surrendering of oneself (istislām). Anything else is rejected (mardūd) and the path to salvation for its follower is blocked (masdūd).
[3:19 cont'd] Those who were given the Scripture, differed only after the knowledge came to them through transgression among themselves. And whoever disbelieves in God's signs, God is swift at reckoning.
Knowledge (ʿilm) came to them which was a proof (ḥujja) incumbent upon them - not [the deeper] knowledge (maʿrifa), which would be clear evidence (bayān) and a path (maḥajja) for them. They persisted in denial (juḥūd) because they were veiled from the place of witnessing (shuhūd).