O People of the Scripture! Do not exaggerate in your religion, and do not say anything concerning Allah except the truth. The Messiah, Jesus son of Mary, was only a messenger of Allah, and His word which He conveyed unto Mary, and a spirit from Him. So believe in Allah and His messengers. (Quran 4:171; see also 66:12)

In the above passage Jesus is called by four noble titles. He is the Messiah, the Messenger of Allah, a Word from Allah, and a Spirit from Allah.

In the same passage, it is clear that the Quran seeks to discourage exaggeration in religion. Further in the same passage, Allah says:

Allah is only One God. Far is it removed from His transcendent majesty that He should have a son. His is all that is in the heavens and all that is in the earth. And Allah is sufficient as Defender. (Quran 4:171)

Refusing to call Jesus son of God is not done with a view to belittle Jesus. No! On the contrary, it is done to Glorify God, to magnify His name, and to proclaim His transcendent majesty.

The Quran confirms that Jesus was born of a virgin woman. When the angel announced to Mary, on whom be peace, that she will bear a child, she said:

My Lord! How can I have a child when no mortal has touched me.

She received the following reply:

So (it will be). Allah creates what He will. If He decrees a thing, He says unto it only: Be! and it is. (Quran 3: 45- 47)

In another chapter, after relating the incidents surrounding the birth of the Messiah, the Quran concludes as follows:

It befits not (the majesty of) Allah that He should take unto Himself a son. Glory be to Him! When he decrees a thing, He says unto it only: Be! and it is. (Quran 19:35)

Jesus – Son of God?

The Quran seeks to correct a common misconception in the minds of people. Many assume that since Jesus had no father then God must be his father.

Glory be to God. He does not father children. He created everyone we know from a man and a woman. But He created Adam from neither a man nor a woman. And He created Eve from a man, but not from a woman. Then, as if to complete the picture, God created Jesus from a woman but not from a man. God has demonstrated His power to create in every way.

God says:

Lo! the likeness of Jesus with Allah is as the likeness of Adam. He created him from dust, then he said unto him: Be! and he is. (3:59)

It is important to realize that Jesus, on whom be peace, never taught that he is the Son of God. God says in the Quran that those who call Jesus “Son of God” are following the saying of other people (see 9:30).

Jesus taught only what he was commanded (5:117). He himself was quite pleased with being a servant of God (4:172).

As a messenger of God, Jesus knew that none in the heavens or the earth can approach God except as a slave (19:93).

Finally, those who say that God has a son should know that they have no warrant for this, but they are saying something without knowledge (10:68).

Source: https://www.whyislam.org.