Fahrenheit 451 contains several Biblical allusions.
One is in "The Sieve and the Sand" when Faber reads from the book of Job. This book of the Old Testament is the story of Job - who is the victim of a dispute between God and Satan, to see if this human, when put through as much difficulty as Satan can manage - will remain faithful to God. Faber encourages Montag to continue doing what he thinks is right, despite the difficulty. In the end, Job does remain faithful - and is greatly rewarded as a result. The unspoken connection here is that Faber believes Montag will feel rewarded in the end.
Another Biblical allusion, also involving Faber (also in "The Sieve and the Sand") is when Faber describes himself as fire and Montag as water. This is a direct reference to Jesus' first miracle - turning water into wine at the wedding at Cana. This allusion draws a parallel between the transformation of the water into wine - which established Jesus' ministry - to Montag's desire for a similar transformation. He has felt purposeless and stagnant his entire life, and hopes his revolutionary idea will pull him out of that purposelessness, and also do something great for humanity.
The other huge Biblical allusion is the reference to the book of Ecclesiastes (the passage Montag is attempting to memorize). If you've ever read Ecclesiastes, you'll know that a key passage is the "everything is meaningless" and "To everything there is a season," lines. No doubt Bradbury chose this book on purpose - as it seems to be a great definition of the two conflicts Montag is most experiencing throughout the novel. First, the "meaninglessness" of his life and second, the desire to change things because the time seems right.
The allusions which I can see so far in Fahrenheit 451 are these ones:
1. When Montag entered the river, came out & changed his clothes, it represents baptism. Once youre submerged in the water when baptised and came out, you're a new being with new "clothes".
2. When Montag is described as fire while Faber water & the 2 combine to form wine, it refers to Jesus' first miracle in Canaan where he transforms water to wine
3. The last line of the book: When we reached the city, this is an allusion to the city of God. THe process where the book people walked there refers to men's struggle to enter heaven
4. Beatty said to Montag of how "we're all sheeps who've strayed at times". This obviously alludes to the story of the Good Shepherd