At different times we may find ourselves sucked into the same lie. We may think that when we sin, it creates separation between us and Christ. Wrong.
A commentary I read on Romans 8:35-39 de-mistifies this beautifully:
"To begin with, God does not shelter us from the difficulties of life because we need them for our spiritual growth (Rom 5:3-5). In Rom 8:28 God assures us that the difficulties of life are working for us and not against us. God permits trials to come that we might use them for our good and His glory. We endure trials for His sake (Rom 8:36), and since we do, do you think that He will desert us? Of course not! Instead, He is closer to us when we go through the difficulties of life.
We are "more than conquerors," literally, "we are super-conquerors" through Jesus Christ! He gives us victory and more victory! We need not fear life or death, things present or things to come, because Jesus Christ loves us and gives us the victory. This is not a promise with conditions attached: "If you do this, God will do that." This security in Christ is an established fact, and we claim it for ourselves because we are in Christ Nothing can separate you from His love! Believe it - and rejoice in it!"
No, in all these things we are more than conquerors through him who loved us. For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.
(From The Bible Exposition Commentary. Copyright © 1989 by Chariot Victor Publishing, and imprint of Cook Communication Ministries. All rights reserved.)