Yes indeed, it is the two-part testimony or declaration of faith by which the one who utters it enters into the fold of Islam. This testimony of faith is the foundation upon which Islam is based. The first half of the testimony constitutes what is also known as al-kalima, which literally means 'the word' Laa ilaaha illallah . That is, the slave must believe that Allah is the only true God, and therefore must not dedicate any act of worship to other than Allah. Conditions Of The First Half Of The Declaration Confessing the testimony of faith must be coupled with fulfilling its seven conditions.
Every door has a key that unlocks it.
These conditions may be analogized with the teeth of that key in order that it function properly. Though one may have indeed entered Islam upon uttering the words it can also be said that complete faith cannot be attained unless he fully understands the implications of his testimony. Knowledge which negates Ignorance. The more a believer knows about Allah and His Deen the less likely is he to fall prey to the traps of Satan and more likely to benefit himself and others. Certainty which negates Doubt.