Shahada is an Islamic creed declaring belief in the Oneness of Allah (SWT) ( الله سُبْحَانَهُ وتَعَالَى) and the acceptance of Muhammed (SAW) (صلى الله عليه وسلم ) as His Last Messenger/Prophet.
The first pillar of Islam is to believe and declare the faith by saying the Shahada or better known as the Kalimah.
One to say it verbally and firmly believe that with his/her own will. No one can force another individual to say the Shahada, it has to come from his/her own free will.
Shahada in Arabic
أشهد أن لا إله إلاَّ الله و أشهد أن محمد رسول الله
Esh-Hadu Ina La E-LaHa illa Allah wa Esh-Hadu Ina Mohammed Rasoul Allah.
I testify there is no God, but Allah (SWT) ( الله سُبْحَانَهُ وتَعَالَى), He has no partners. Muhammed (SAW) (صلى الله عليه وسلم ) is His last Messenger and Prophet.