Statements that could lead to kufr

There are times when we motivate brothers to excel in the workplace and at school and the following statement is uttered “We believe in you” but not in the sense that we really believe in the brother as we we only believe in Allah Most High. We merely utter it to motivate the brothers so will the above statement be tantamount to kufr? Please elaborate on what kind of statements would lead to kufr whether said jokingly or either ignorantly?