Can we enjoy God's fellowship regardless of how well we behave?
Yes. Since believers are justified by faith, they have peace with God through the Lord Jesus Christ and are no longer enemies. Their standing does not depend on how well they behave. They can enjoy His fellowship moment by moment, retaining constant fellowship because justification secured peace with God.
Les explains from Romans 5:1 that being justified by faith puts the believer back like Adam before the fall: God has reckoned the old sin nature dead and gone, and the believer is declared just as if he had never sinned. The slate is wiped clean, so the believer has peace with God through the Lord Jesus Christ. The unbeliever can never experience this peace and lives in turmoil, but the believer does not have to live in constant turmoil or fear that God will zap, disown, or cast him out. Justification brings peace with God, so we are no longer enemies but are His, and we can enjoy His fellowship moment by moment regardless of how well we have behaved. This constant fellowship remains because of our justification, which gave us peace with God. Philippians 4 then speaks of the peace of God.
Therefore being justified by faith, we have peace with God through our Lord Jesus Christ: