Rm8

When the bible says that "nothing can separate us from the love of God" it means NOTHING can separate us from the love of God! Our salvation is rooted and sealed by God! All His works are permanent and rooted in His activity NOT ours. 

When we begin to believe that our relationship with God is somehow rooted in our activity, we begin to treat God as though He is human. He is not. His relationship with us is HIS choosing. His choices are eternally permanent. What He does, He does for good. God is not fickle or capricious. His love for us has been poured out through Jesus.

There is nothing more "guaranteed" in this life than the permanence of God's love for those He has saved. Eternity is secure. Don't let doubt and condemnation (struggles we all have) become the things that rob our joy and keep us from living for Christ.