1. Islamic Philosophy

2. Muʿtazilah Wasil ibn Ata (700–748)
Mu'tazilis (8th century): Rationalistic theology
1. God is one and unique: he is not a body, person, substance; he absolutely transcendent. His attributes are not eternal such as: knowledge, will, language.
2. Qur'an = created.
3. Justice: me has a free will.
4. Human reason is decisive to interpret the Qur'an, but reason is not sufficiently powerful to know everything. For this reason humans need revelation in order to reach conclusions concerning what is good and what is bad for them.
This negative philosophy meets with negative theology of other religions.

3. Ash'arites
Theologian Abu al-Hasan al-Ash'ari (73-935): critique of Mu‘tazilis‘ rationalism: Qur'an and tradition stay over reason.
God‘s attributes are eternal, even the Koran.
Men‘s actions are made by God; human beings only can gain the disposability to act.
Revelation keeps its significance against reason.
Revelation seems to be the right orientation.

4. Avicenna – Abu Ali ibn Sina (+1037)
Against Aristotle: Philosophy of being (existence – essence)
Things are only possible, the need an act of being; God as the necessary being.
„eternality of the world“
Metaphysics of the human soul: immaterial, immortal, individual.
Salvation: completion of the own soul by knowledge (contemplation, mysticism)
The prophets get their knowledge by intuition and participation on the cosmic intellectus agens.

5. Al-Ghazzali (*1058) Critique of philosophy and reason
Certainty only by grace and spiritual intuition
“The Incoherence of the Philosophers” (20 chapters):
Refuting
- the doctrine of the world's pre-eternity.
- the doctrine of the world's post-eternity.
Demonstrating:
- the inability of philosophers to prove the existence of the Creator.
- the inability of philosophers to prove the impossibility of the existence of two gods.
- their inability to demonstrate that the First is not a body.
- their inability to show that the First knows others.
- their inability to show that the First knows Himself.
Refuting - that the First does not know the Particulars.
- their doctrine that disruption of causality is impossible.
- their statement that the human soul is a self-sustaining substance that is neither a body nor an accident.
- their denial of bodily resurrection and the accompanying pleasures of Paradise or the pains of Hellfire.

6. Adolkarim Sorush (*1945)
There is only interpretation: faith is the history of its interpretation; Qur'an exists being interpreted.
God reveals himself to human persons in an always different way; there is no exclusive form of revelation.
Being Muslim, Jewish, Christ depends the tradition in which one grew up. In this one can discover a providential plan.

7. Conclusion
Due to a understanding of revelation (and salvation) as knowledge, philosophy is considered as a possible form to improve and to control theological insights.
Revelation completes rational knowledge.
Religions will be considered as possible contributions to the issues of reason.
Due to the understanding of salvation as unity with God and due to the emphasize of God‘s and humans‘ will, there is the question if revelation does not have more developed and understood in historical terms in correspondence to its eventfulness?

8. Christian Philosophy of Religion

9. Against PTR: Philosophical Concept of God
IF the absolute reality, has to be thought, then, according to Hegel, it gets logically difficult to banish the absolute completely out of finite reality without limiting the absolute in a contradictory way.
Only a God in an Aristotelian sense may have no contact with finite reality because this God is not the creator. But an independently existing reality beside God seems to limit the absolute‘s absoluteness.
Ergo: is seems to be more consistent to think the absolute as a reality able to be present in its „otherness“, that is, in finite reality.

10. Philosophical approach to God‘s greatness
Joseph Ratzinger (Introduction to Christianity [1968], 146):
Ratzinger reflects on the presupposed incompatibility of God and finitude/ history arguing for the possibility of God‘s revelation and incarnation. R. cites a remark of the poet Hölderlin to capture the Christian image of the true greatness of God: “Non coerceri maximo, contineri tamen a minimo, divinum est” (“Not to be encompassed by the greatest, but to let oneself be encompassed by the smallest: That is divine”). For God, nothing is too small. “Precisely this overstepping of the greatest and reaching down into the smallest is the true nature of absolute spirit.” (146)

11. Against PTR: Philosophical Concept of definite sense
The ethical approach of the PTR presupposes the possibility and the sense of conversion from self-centeredness to reality-centeredness: that the entire reality is coined by mutual recognition, which we have to presume even in the case of the absolute.
Therefore, salvation is made in history, in a contingent reality which must me more than „appearance“: mutual recognition is realized in the moment in which the human persons reveal the reality to each other as such, in their selves. This concerns the absolute as well to which reality-self-centeredness is addressed to.

12. Philosophical approach to definitive sense (anthropology)
Joseph Ratzinger (Introduction to Christianity, 269):
The free given and contingent as the real necessary: „It seems to me that from here squaring of the theological circle, so to speak, can be accomplished; that the intrinsic necessity of apparently historical contingency of Christianity can be shown, the „must“ of its – to us - objectionable positivity as an event that comes from outside. This antithesis, so heavily emphasized by Lessing, between vérité de fait (contingent factual truth) and vérité de raison (necessary intellectual truth) here becomes surmountable. The contingent, the external is what is necessary to man; only in the arrival of something from outside does he open up inwardly. God‘s disguise as man in history „must“ be – with the necessity of freedom.“

13. Conclusion
A theory of religion which does not serve as a definitive contact of an absolute God and human history in which absolute sense occurs, does not correspond to a philosophical criterion of God‘s absoluteness and human necessity.

14. A proposual: Definitive sense and mutual inclusivism
Incarnation as an event of definitive (absolute) sense.
This absolute sense gives rise to a manifold cooperation.
This cooperation is given by the salvific center of the non-Christian religions: …is given by other events or communication of sense.
According to each religion the sense- constituting center of the other religions are participated forms of mediation of different kinds and degrees which the own center gives rise.
A mutual inclusivism could be a form which describes the reciprocal relationship of religions without relativizing their historical and salvific basis.
"Teilhabende Mittlerschaft" und wechselseitige Inklusion. Zur Christozentrik des interreligiösen Dialogs, in: Rivista teologica di Lugano 6 (2001)
"Mediazione partecipata" e inclusione mutua. Sul cristocentrismo del dialogo interreligioso, in: L'attuale controversia sull'universalità di Gesù Cristo, a cua di M. Serretti, Roma 2002, 51-66

15. Andreas Grünschloss
Andreas Grünschloss, Der eigene und der fremde Glaube (HUTh 37), Tübingen 1999, 303:
„Versuche andere stets so zu verstehen, wie du auch selbst verstanden werden möchtest.“ = die Goldene Regel des interreligiösen Dialogs
Philosophy is an important device to understand and to evaluate the truth-claims of the own one and of the other religion.