Each Abrahamic religion has its own conception of this unusual being.
It is impossible to reconcile those conceptions given the considerable disparity among them.
The Holy Spirit in Islam
In Islam, the Holy Spirit is Gabriel, who is an angel of God. He is sometimes mentioned by the name “Gabriel”, whereas he is sometimes referred to, inter alia, as “Holy Spirit”.
He is exclusively named “Holy Spirit” to the exclusion of the other angels given his central role in the revelation of the Holy Scriptures and his support of the prophets of God and godly people.
Scholars sought to account for “Spirit” as an exclusive name of Gabriel unlike the other angels. Al-Jayyani remarked: “he was called ‘Spirit’ for selves are livened by him just as they are livened by spirits.”
Ar-Razi followed by Ibn Adil noted: “he was called ‘Spirit’ for he was created from God’s Spirit.” It is said that he is given this name “for he represents salvation for all creation in terms of judgment. So he is like a spirit which gives life.” It is also said “for he is wholly a spirit unlike the human beings who have both bodies and spirits.” He is called “trustworthy” for he was entrusted with the revelations conveyed to prophets and others.
The evidence for Gabriel being “the Holy Spirit” is the frequent reference to him that it is he who brought down the Quran to Prophet Muhammad and that it is he who supports him along with the other prophets. Such are some of the qualities of the Holy Spirit as set out in the Quran.
About bringing the Quran down by Gabriel, we read in the Quran:
Say, “Whoever is an enemy to Gabriel – it is [none but] he who has brought the Qur’an down upon your heart, [O Muhammad], by permission of Allah, confirming that which was before it and as guidance and good tidings for the believers.” (Al-Baqarah 2:97)
About his support of Prophet Muhammad, we also read:
If you two [wives] repent to Allah, [it is best], for your hearts have deviated. But if you cooperate against him – then indeed Allah is his protector, and Gabriel and the righteous of the believers and the angels, moreover, are [his] assistants. (At-Tahrim 66:4)
About bringing the Quran down by the Holy Spirit, we read in the Quran:
Say, [O Muhammad], “The Holy Spirit has brought it down from your Lord in truth to make firm those who believe and as guidance and good tidings to the Muslims.” (An-Nahl 16:102)