Crucial Questions Series by R.C. Sproul
You can download all the books for free, or chose any that are of interest to you.
If you prefer a daily devotional on your computer, phone or tablet, please enjoy Solid Joys on Spotify, Google Podcasts, Apple Podcasts, or on Desiringgod.org
New Morning Mercies: A Daily Gospel Devotional, I recommend this book more than any other daily devotional I’ve seen. It’s not free, but worth either the hard cover or Kindle version.