Thinking is the mind’s speaking, and the Heart-searcher can, and does more easily take notice when the mind thinks impertinently, than we can observe when the tongue speaks so.
To think God’s thoughts requires much prayer. If you do not pray much, you are not thinking God’s thoughts. If you do not read your Bible much and often and reverently, you are not thinking God’s thoughts.
The thoughts dwell upon an act or course of action with interest and consent; this stirs the affections which in turn trigger off the will to act under contemplation. The sin that follows may be so base, so physical, so obviously ‘of the flesh’ that no one would dream it began as an undisciplined thought in the heart.