What is Assurance

According to wikipedia : Assurance service is the independent professional service, with the goal improving the information or the context of the information so that decision makers can make more informed, and presumably better decisions. Assurance services provide independent and professional opinions that reduce the information risk (risk that comes from incorrect information).
Calvinism teaches that believers may have assurance of their salvation especially through the work of the Holy Spirit and also by looking at the character of their lives. If they believe God's promises and seek to live in accord with God's commands, then their good deeds done in response with a cheerful heart provide proof that can strengthen their assurance of salvation against doubts. This assurance is not, however, a necessary consequence of salvation, and such assurance may be shaken as well as strengthened

Calvinism teaches that believers may have assurance of their salvation especially through the work of the Holy Spirit and also by looking at the character of their lives. If they believe God's promises and seek to live in accord with God's commands, then their good deeds done in response with a cheerful heart provide proof that can strengthen their assurance of salvation against doubts. This assurance is not, however, a necessary consequence of salvation, and such assurance may be shaken as well as strengthened