Christians are people who follow or adhere to Christianity, a monotheistic Abrahamic religion based on the life and teachings of Jesus Christ.
A scriptural perspective: According to Qur'an and hadith, it is good to share the message of Islam and invite others to it (what is known as da'wah). This should be done in a good way, with politeness and good forms of discussion and argumentation.
However, nothing in Islamic texts that says that conversion for the sake of conversion is a goal. There is no real point to false conversion or forced conversion. The Qur'an and Islamic worldview acknowledge the existence of people of other faiths and that there is good and bad in other faiths. It is said that at the end of time when the Mahdi (the promised saviour/last imam) arrives, many people will convert to Islam because it will be clear that he has a true and good message. However, texts also indicate that some people will remain with their own religions and not convert to Islam.
Many regions that today are majority Muslim took time to convert to Islam. This process happened gradually, over hundreds of years, and wasn't instant, even though the rulers of many of these regions identified as Muslim. Probably this is because while conversion is a social phenomenon, it is also a highly individual one, and individuals have different reasons for religious conversion. Sometimes there is a conflation between the expansion of the original Arab-Muslim Empires and conversion to Islam, but in reality just because the borders expanded did not mean that everyone in these territories suddenly became Muslim.
A sociopolitical perspective: The Islamic world today does not have a single goal. While it would be ideal if Muslim-majority countries and Muslim leaders could unite (especially on the basics, such as economic cooperation), currently, this is not happening. Individual Muslim leaders and Muslim groups have their own goals. By and large, I think most Muslims today are more concerned about internal issues (politics, the threat of war) or questions regarding Islam and contemporary life, rather than expansion. Islam is already a large religion and isn't in danger of disappearing due to numbers. Also, most Muslim-majority countries have historically established religious minority communities. That being said, there are some Muslims who do work at spreading the message of Islam.
In any case, Islam is still spreading (particularly in the West and parts of Africa, but also - although there is less attention to it - in Muslim-majority countries and India). There is some interesting literature on the dynamics of the history of the spread of Islam if you wish to explore it.
Jesus (AS) is alive in the sky, s here is no question of resurrection.
What many Christians believe today does not mean necessarily the real teachings of Jesus (AS).
Truth must be said and no one knows The Full Truth more than Allah.
We must say what Allah (SWT) said in Qur'an. The Truth does change because of people.
Jesus (AS) did not die and he is still alive in the sky and will come back to the earth in the time of the re appearance of Imam Al-Mahdi (AS). This fact will make the Muslim World and Christian World closer to each other.
There is no question of any meat to be Halal without fulfilling all conditions of Halal meat including the condition of a Muslim slaughter. Any animal slaughtered by non Muslim can never be Halal.
You are able to do an 'aqiqah for yourself. Please just keep in mind that it is best that all the mustahabaat / makruhaat of 'aqiqah are considered.
There are a few options that you can choose to get this done.
1. Contact your local Muslim butcher, and ask if they do 'aqiqah sacrifices.
2. Visit your local Islamic centre and speak to them if they can accept the responsibility of doing the aqiqah on your behalf, after you pay its amount.
3. Contact trustworthy Islamic charity organisations, and ask if they have an animal sacrifice program, where they distribute the meat to the poor and needy.
With prayers for your success.
Muslim is not allowed to attend or take part in any non Muslim religious ceremony.
The child mentioned in your question is a Muslim because of his Muslim father. Islam says that any child who is born from Muslim father or Muslim mother, is a Muslim.
الولد يتبع أشرف الأبوين
There is no question of baptism ceremony for a Muslim child.
Islam orders every husband to take full responsibility of his wife and children including living expenses.
There is no doubt for any one with minimum knowledge about the history of the different Jewish and Christian scriptures that they are not the original scriptures revealed on Moses and Jesus, but were compiled long time after them.
The different Torahs and different Bibles existing today are living evidence that the original scriptures are mot in the hands of people.
Hanifs or Ahnaaf are those who remained on the faith of Ebrahim (AS). There were neither Jewish nor Christian. Prophet's father, grandfather and Abu Talib, the uncle and protector of the Prophet (SAWA) were on that faith of Ebrahim (AS).
The Prophet Muhammad (SAWA) never attended any Jewish or Christian theologian.
Any type of aggression against any human being , Muslim or non Muslim and even against peaceful animals or nature is very bad and Allah does not like the aggressors.
The significance of marriage is to the extent that it is said that one will save half of his/her religion by getting married. It means that the potentiality of getting involved with sexual sins decreases by getting married.
As for the second part of your question, according to the popular viewpoint of Maraje' a Muslim man can marry an ahlul kitab i.e. Christian, Jew or Zoroastrian woman in temporary marriage only and not vice versa.