Why would Allah SWT do such thing? What is the message?
Not only the fatherless birth of Jesus (pbuh) but also many other signs which Allah showed to Children of Israel were to attract the lost sheep of Israel back to God.
I can think of mainly 2 reasons.
These miracles i.e. fatherless birth, Jesus (pbuh) raising dead people, giving life to bird made of clay etc, these were the clear signs shown to those people, in a hope that they'll increase their belief in God.
To show that Allah can do anything, i.e. let even the impossible happen. And he is able to do all things.
Why was Maryam accused of بغاء Bigha or بغيا Baghiyya?
Well just imagine today a woman conceiving a baby without any man touching her. It would be hard to believe ryt? So, similarly, the Jews at that time, didn't believe that she was gifted a baby directly from God, and rather accused her of having unlawful baby.
what was Allah SWT answer to this accusation?
The answer is this...
Therefore, for their (Jews) breaking their covenant and their disbelief in the communications of Allah and their killing the prophets wrongfully and their saying: Our hearts are covered; nay! Allah set a seal upon them owing to their unbelief, so they shall not believe except a few. (Qur'an 4:155)
And for their disbelief and their speaking against Maryam (Mary) a tremendous all-malicious (calumny). (Qur'an 4:156)
May the creator guide us all.
