If our thoughts are kind, peaceful and quiet, turned only towards good, then we also influence ourselves and radiate peace all around us—in our family, in the whole country, everywhere. When we labor in the fields of the Lord, we create harmony. Divine harmony, peace and quiet spread everywhere. However, when we breed negative thoughts, that is a great evil. When there is evil in us, we radiate it among our family members and everywhere we go. So you see, we can be very good or very evil. If that's the way it is, it is certainly better to choose good!
St. John Chrysostom teaches us that all evil comes first from ourselves and only secondly from the devil. If we keep our minds vigilant and our hearts strong in the Faith, the devil has no access to us.
Elder Thaddeus of Vitovnitza