Once a Bedouin came to Rasulullah (Sallallahu Alaihi Wasallam). Rasulullah (Sallallahu Alaihi Wasallam) asked him; "Do you bear witness that there is none worthy of worship besides Allah and that I am His Messenger?" The Bedouin bluntly answered: "No!" This Bedouin then pointed to a live lizard that he had and said: "I will not accept you until this lizard bears witness that you are the Messenger of Allah." Rasulullah (Sallallahu Alaihi Wasallam) said: "Give it to me." He then held it in his hands and addressing the lizard asked: "Who am I?"
The lizard said: "I bear witness that you are the Messenger of Allah." Upon hearing this and witnessing this miracle the Bedouin proclaimed the Shahadah and accepted Islam. He then went to his nation and invited them towards Islam. Hence they also accepted Islam. This was all due to the kindness and tolerance of Rasulullah (Sallallahu Alaihi Wasallam).
Similarly Rasulullah (Sallallahu Alaihi Wasallam) was once sitting in the Musjid with his companions. A Bedouin came into the Musjid and began urinating in one corner. The people became furious and harshly rebuked him. Rasulullah (Sallallahu Alaihi Wasallam) said to them: "Leave him alone. Do not rebuke him." When this person had relieved himself Rasulullah (Sallallahu Alaihi Wasallam) instructed one of the Sahaaba (R.A.) to bring a bucket of water and purify the place. He then called the Bedouin and gently said to him: "This is the Musjid - the house of Allah. This is the place to perform Salaah, recite the Holy Quran, tasbeeh, etc. It is not the place to relieve oneself." Rasulullah (Sallallahu Alaihi Wasallam) thus advised him with soft and gentle words. The Bedouin went outside and after mounting his camel said: "O Allah have mercy on Muhammed (Sallallahu Alaihi Wasallam) and myself. Do not have mercy on anyone besides us." Due to the kindness of Rasulullah (Sallallahu Alaihi Wasallam) the Bedouin loved him and prayed for him. As for those who had rebuked him, he excluded them from hisDua.
Hence it is necessary to adopt love, kindness and gentleness in the course of inviting towards Allah Ta'ala. If people are invited with kindness they will accept. Harshness will only drive the people away.
It is also necessary, especially in these countries, that one should adorn oneself with the qualities of a true Believer. He should apply all the commands of Deen upon himself. This includes being punctual upon Salaah with Jama'ah(congregation). One should refrain from all sins and transgression. One should refrain from disobedience, adultery, drinking, stealing, transacting in interest, lying, backbiting, deceiving, not paying people their dues - even if they be non-Muslims. He should deal with compassion and kindness. Likewise he should fulfil his promises. These are the qualities of a Believer. When one will adorn oneself with these qualities, he will be loved by the people. Hence this will attract them to Islam and they will eventually accept it.