I'm an Adventist Christian who enjoys reading non-Adventist authors.
When reading or listening to someone who I know doesn't share everything with me doctrinally, I apply the watermelon principle (eat the fruit, spit out the seeds), because Jesus was clear with us that not all of His sheep are of the same fold, and it would be a crying shame to let such an abundance of heartfelt Christian writings go to waste - to disregard other believers investing their talents according to the best light they have, to assume the Holy Spirit is absent from their lives due to doctrinal differences - when there are great portions that can so richly bless the heart and provoke deep thought.
We should never forget that the Holy Spirit is always working to bring people fully into the light - it is a process. Their steps into and stances that are in the light should be affirmed and appreciated. And as I read, I test what I read by Jesus' principle of knowing something by its fruits. Non-Adventist authors have actually played irreplaceable roles in strengthening my Adventist faith and drawing me BACK to the Bible and BACK to church in my younger years. And I believe this happened as a testimony to the humble and authentic spirit certain authors write from and as a testimony that we should not assume God only works through Adventist authors.
Ironically, the place where Christian denominations can most easily overlap is in the area of having a relationship with God, building trust in Him, learning to know His personal love for us, deducing His character from His Word. As I think about it, I am touched that it is no mistake that what I've just described is the area of overlap. Because once a personal relationship with God of strong trust is built, a person is then poised to be willing for Him to lead them into the unchartered waters of...per se...changing their views on doctrines they might have held for a long time, just like Abram's trust in God meant He let God lead him away from his home.
Yes, there are doctrines that should not be compromised on, ever. AND, there are areas where believers cannot help but OVERLAP, and it is THERE that I read to continue honing my perspective. Because the topics of doctrine - once you've fully arrived - can plateau; there's only so much to learn, and then you know. But the journey of trusting God on this side of heaven is unending and continually assaulted by Satan and our sinful nature - no matter how much *information* you cognitively possess - and so I will gladly and gratefully read from other believers shining their light, sharing their encouragement as best they can.