I have a friend of mine who is a Christian and keeps telling me that (xxx) is getting signs to find a verse in the bible that he is the son of god. Also this (xxx) was healed from demons when he went to church one day by the announcement of Lord Jesus. This (xxx) had a toothache before and was healed in church by this priest who put his hand on this (xxx) shoulder. Could you please provide explanation for these situations? I am a Muslim brother but could not respond to this person at the same time I do not think this person is right.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

First of all, we advise you not to indulge in discussions with Christians except in matters that you are certain about. It is better to take this Christian to a Muslim scholar who can talk with him in a wise manner and with knowledge.

Moreover, we advise you to keep company with righteous Muslim friends. Bad friends, though they are Muslims, badly affect you, let alone if if they are non-Muslims. Know that befriending non-Muslims weakens the concept of love and enmity for the Sake of Allaah.  Allaah Says (what means): {…Take not the Jews and the Christians as Auliya' (friends, protectors, helpers, etc.),… }[Quran 5:51]. Allaah also Says (what means):{You (O Muhammad SAW) will not find any people who believe in Allaah and the Last Day, making friendship with those who oppose Allaah and His Messenger (Muhammad SAW), even though they were their fathers,…}[Quran 58:22]   

As for what you mentioned in your question, know that sometimes Allaah might respond to the supplications of a non-Muslim and grant cure to a sick person as a trial and examination by Allaah.  Sometimes such things occur by the devil who is fond of leading people astray, especially those who do not have deep knowledge and strong faith.

However, if someone claims that he is son of God or claims that someone among the creatures is son of God, then this is totally null and void as known by absolute evidence in the Sharee'ah, logically and by the Fitrah (the natural predesposition upon which Allaah created mankind).

There is much Isalmic evidence on this, for example Allaah Says (what means): {"He begets not, nor was He begotten}[Quran 112:3] 

Logically, whoever begets a son needs him, while Allaah does not need anything, but all the creatures are in need of Him.  Glorified and Exalted is He from the great falsehood that they say.

Also, by nature, anyone who has a sound Fitrah denies such false and illogical claims.

Allaah Knows best.