1. Verse 48 recounts the august virtues of Sayyidna ` Isa (علیہ السلام) who would be born blessed with the honour of learning from Allah: Scriptures, Wisdom and specially the توراۃ Torah and the اِنجیل Injil; and that he will be sent as a Messenger of Allah to all of the Children of Isra` il.
2. The message he will carry to them will be his argument in favour of his prophethood. In order that they believe, enumerated in verse 49, there are four signs or miracles that he would perform, being enough for willing believers.
3. Verse 50 says that Sayyidna ` Isa (علیہ السلام) will declare that he has come to confirm Torah which was revealed before his coming and to make lawful what remained unlawful for them in the law of Moses. This means that the unlawfulness of some things in the earlier code would stand abrogated by the new one, (that of Sayyidna ` Isa علیہ السلام) whose station of prophethood was the conclusive argument for that claim of abrogation. The proof of his truth were the signs from their Lord.
4. Once his prophethood is established, verse 51 states that Sayyidna ` Isa (علیہ السلام) will ask them to beware of any contravention of Divine commandments, fear Allah, and follow his teachings in matters of religion which, in a nutshell, are that 'Allah is my Lord and your Lord' (the ultimate in belief) and 'Worship Him' (the ultimate in deeds). This, then, is the straight path which helps perfect the ideal combination of beliefs and deeds, leads to the way of salvation and is the source of communion with Allah.
Ruling:
Making the shape of a bird was the making of a picture, something permitted in that Shari` ah. In our Shari'ah, its permissibility was abrogated.