Is this for a young person or adult? Also, what about podcasts or audio things? Would any of that be okay.
But, I'm going to think outside the box a bit - how about going back to the early church writers. There's some very good writings within the first 400yrs of the church... and much of it is surprisingly accessible to today's audience.
Justin Martyr's Dialog with Trypho is quite enlightening and he was writing circa 150AD.. widely available online - it's not that long either.
On the Incarnation by St. Athanasius is also quite good- it's also less than 100pages long... if you buy the book with the forward by CS Lewis - it is FANTASTIC. Honestly, just the Lewis' introduction is worth the price of the book