Welcome again dear Râhib
If anyone has a real desire to be a Muslim and has full conviction and strong belief that Islam is the true religion ordained by Allah for all human-beings, then, one should pronounce the "Shahada", the testimony of faith, without further delay. The Holy Qur'an is explicit on this regard. There is a versein the Qur'aan which means :
"The Religion that Allaah accepts is Islam." (Qur'an )
In another verse of the Holy Qur'an which means:
"If anyone desires a religion other than Islam (Submission to Allah), Never will it be accepted of him; and in the Hereafter he will be in the ranks of those who have lost (their selves in the hell fire)."(Qur'an )
In addition, Islam is the only religion prevailing over all other religions. Allah states in the Holy Qur'an:
"To thee We sent the Scripture in truth, confirming the scripture that came before it, and guarding it in safety:..." (Qur'an )
Mohammad, the Prophet of Allah (Peace and blessing of Allah be upon him), said what means:
"The most important matters of Islam are five: testifying that there is no God but Allah (i.e. only Allaah deserves to be worshipped), and that Mohammad is the messenger of Allah, performing the prayer, paying the Zakah, fasting the month of Ramadan, and performing Hajj".
The Shahada can be declared as follows:
"ASH-HADU ANLA ELAHA ILLA-ALLAH WA ASH-HADU ANNA MOHAMMADAN RASUL-ALLAH".
ÇÔåÏ Çä áÇ Çáå ÇáÇ Çááå æÇä ãÍãÏÇ ÑÓæá Çááå
The English translation is:
"I bear witness that there is no God but, Allah, and I bear witness that Mohammad is the messenger of Allah",
However, it would not be sufficient for anyone to only utter this testimony oraly either in private or in public; but rather, he should believe in it by heart with a firm conviction and unshakeable faith. If one is truly sincere and complies with the teachings of Islam in all his life, he will find himself a new born person.
What do the words of the "Shahada" signify? The significant point which every Muslim must know very well is the truth that there is no God (deity) to be worshipped other than Allah. He - glory be to Him - is the only true God, Who alone deserves to be worshipped, since He is the Giver of life and Sustainer and Nourisher of mankind and all creation with His unlimited bounties. Man must worship Allah, Who alone is worthy of worship.
The second part of the Shahada (i.e., Wa ash-hadu anna Mohammadan rasul-Allah) means that Prophet Mohammad is the servant and chosen messenger of Allah. No one must have two opinions about this matter. In fact the Muslim has to obey the commands of the Prophet , to believe him in what he has said, to practice his teachings, to avoid what he has forbidden, and to worship Allah alone according to the message revealed to him, for all the teachings of the Prophet were in fact revelations conveyed to him by Allah.
"... whoever rejects evil and believes in Allah hath grasped the most trustworthy Hand-hold, that never breaks..." (Qur'an )
ALLAH bless you my dear friend