Going out for da’wah

I have some questions which I hope you can answer in full.
1 – Some friends and I go and visit people in their homes and on the sea and on the street to remind them of Allaah and call them with that which is better. Is this action incorrect, and is it regarded as visiting people for the sake of Allaah, because that is our intention?
2 – Sometimes my brothers in Islam and I go to Africa and many countries to call people to Islam, and they turn to Islam in an amazing manner, and they are even moved by our appearance, let alone when we speak to them. How sound is this action, given that some people say that this is bid’ah and that we should have a great deal of knowledge, even though the people there do not know anything about Islam, and if we simply call them and explain the religion to them they become Muslim?
3 – What is the ruling on going out for da’wah for the sake of Allaah and freeing up one's time for that, even though some people told me that I should not go out with the people who do da’wah because they are innovators, although I have not noticed anything like that, rather what I have seen with my own eyes is that they are reviving the Sunnahs of the Prophet (peace and blessings of Allaah be upon him) and holding dhikr circles and study circles to teach the Sunnahs of the Prophet (peace and blessings of Allaah be upon him) from Riyadh al-Saaliheen and encouraging people to pray qiyaam al-layl etc. Please advise us, may Allaah reward you with good.

Praise be to Allaah.
Your question covers several issues:

1 – This action that you and your friends are doing, calling people to Allaah, is something that is to be appreciated at a time when few people are doing such work. We give you the glad tidings of the words of the Prophet (peace and blessings of Allaah be upon him): “Whoever points others towards doing good will have a reward like that of the one who does it.” Narrated by Muslim, 133.

If by doing this work you intend to visit others for the sake of Allaah, then this is how it will be, in sha Allah.

2 – Do not let the blame of anyone put you off from doing this work, so long as you and your brothers are calling people with proper knowledge and insight, as appears to be the case from what you say.

3 – If the people you mention are known to have sound ‘aqeedah and knowledge, and are known for their good conduct and attitude, then there is nothing wrong with cooperating with them in da’wah and going out with them, whether that is for a short time or a long time, because Allaah says (interpretation of the meaning):

“Help you one another in Al‑Birr and At‑Taqwa (virtue, righteousness and piety)”

[al-Maa'idah 5:2]

“And who is better in speech than he who [says: ‘My Lord is Allaah (believes in His Oneness),’ and then stands firm (acts upon His Order), and] invites (men) to Allaah’s (Islamic Monotheism), and does righteous deeds, and says: ‘I am one of the Muslims’”

[Fussilat 41:33]

“Invite (mankind, O Muhammad) to the way of your Lord (i.e. Islam) with wisdom (i.e. with the Divine Revelation and the Qur’aan) and fair preaching, and argue with them in a way that is better”

[al-Nahl 16:125]

And the Prophet (peace and blessings of Allaah be upon him) said to ‘Ali (may Allaah be pleased with him) when he sent him to Khaybar to call the Jews to Islam: “By Allaah, if Allaah were to guide one man through you, that would be better for you than having red camels [the best kind].” Narrated by al-Bukhaari, 3701; Muslim, 2406

The Prophet (peace and blessings of Allaah be upon him) sent daa’iyahs (callers) to Yemen and to many of the Arab tribes.

Many members of this group with whom you are going out are lacking in Islamic knowledge, and they may hold some false beliefs, but this should not prevent you from going out with them and calling people to Allaah; rather you should go out with them and explain the truth to them, and teach them what they do not know of the Sunnah, and advise them to give up the innovations that they do. Perhaps Allaah will benefit them through you.

And Allaah knows best.

Please see also questions no. 8674 and 39349.