God is charity (1 John 4:8 & 16)
Christians believe in the Triune God, the God who is described as being love (charity). In this post, I will examine why the claim "God is love" is only logical and reasonable when we speak of the Triune God, the one God and Creator of all. Actually, one could go further and say that - if God is love - then - by necessity - only the Triune God is the one true God and no other.
Now this may be a scandalous claim to non-Christians. Therefore, we should proceed with the examination of this claim.
I will start right away with the great monotheistic religions; Judaism and Islam. One thing to note is that Jews and Christians believe in the same God. The only difference is that Jews who do not accept Jesus as the Christ have then refused to accept Divine Revelation regarding the essence of the nature of God. God revealed Himself as a Trinity, as love.
While the anti-Christian Jewish view of God certainly cannot come close to the truth stating "God is love", we have to realize that the error is not on part of God, but on part of those people who refuse to accept Divine Revelation. Wherefore, the Jews still believe in the same God, but have a lesser understanding of - the same - God than Christians.
Muslims on the other hand believe in Allah. It is important to point out that Allah and God are not the same. While some Jews and all Muslims are strict monotheists - thus denying the Trinitarian nature of God - it does not follow that both believe in the same God, for this is not true. The concept of "Allah" is one created from aspects "borrowed" from other religions (mainly Christianity and Judaism). Since the Qur'an (Islam's "holy book") explicitly states that Jesus is not God and thus authoritatively denounces the truth as divinely revealed in the New Testament (the continuation and fulfillment of the Old Covenant), we cannot say that both the Qur'an and the Bible are from the same God; truth does not oppose truth. Judaism came before Christianity making Christianity the organic progress in terms of Divine Revelation. Islam however does not progress but seeks to destroy that which has been revealed in the New Covenant. Therefore, Allah is not God.
It is now time to compare the two: Allah and the Triune God (the God of Jews and Christians).
Allah is one. While one can say that "Allah loves", one cannot reasonably argue that "Allah is love". And that is precisely the important difference. If Allah is love, then - before all creation - love must have existed within the singularity of Allah. Since Allah is strictly monotheistic (alone), then he would have to love himself. But if Allah is love, then the love with which Allah loves himself has to be Allah too. So Allah becomes subject and object of love with the act of loving being Allah too. This notion however comes close to the Triune God which the Qur'an explicitly negates. Thus the love with which Allah loves himself cannot be Allah, therefore Allah is not love.
Furthermore, there is no true "sharing of love" as Allah would only be "loving himself".
Let us compare this with the Triune God:
The Bible says that God is love. Before anything was created (even angels), God alone must have been love already - otherwise His nature of being love (which ought to be intrinsic) would depend on things created and thus would not be an eternal aspect of His nature. The Trinity is described as being tres personae in una substantia; three persons in one substance.
So we have to have three distinct persons: the Father, Son and the Holy Spirit, but all make up only one God while each one person is fully God. It is hard to understand, but it makes sense.
Now consider: before creation, God alone was this: The Father and the Son loving each other as one God. For the concept of "love" to work, we need a lover, a beloved and the love that is shared by the two. And since we claim that "God is love", the love shared between the two has to be God: it is not created. Thus, the Father is God, the Son is God and the Holy Spirit - the love shared between the Father and the Son - is also God. None of the three distinct persons may be created since we are speaking of a situation prior to any creation; and that which exists prior to all creation is uncaused and eternal; it is God.
At the same time, we speak of three distinct persons - bearing in mind that love has to be shared, otherwise it ceases to be love and since God is eternal and God is love, then love too has to be eternal; thus the relationship between the three distinct persons has to be eternal too.
This relatio inter tres personas uni Dei (relation between the three persons of the one God) is one of love - as explained already. Now it is time to explain the distinction between the three persons without which we cannot claim to actually have a Triune God.
The distinction is best understood and explained by Catholic theology (based on the works of St. Thomas Aquinas). Since all three persons are God and thus co-equal and co-eternal, there may not be a type of subordination between them in terms of power. The distinction therefore is made based on the procession - in terms of origin - of each person. Since we are discussing the intrinsic relationship of the three distinct persons, it would seem reasonable to base the explanation on it.
For the relationship to work, we have:
a) the Father who is without origin: the prime principle
b) the Son who proceeds from or is sent by the Father
c) the Holy Spirit who proceeds from or is sent by the Father and the Son (Filioque)
So, the Father sends the Son who proceeds from Him. Thus the Father has authority over the Son - not in terms of power, but in terms of origin. Therefore the Bible teaches that the Father and Jesus are one - being one God (John 10:30) - and that the Father is greater than the Son (John 14:28).
Likewise the Father and the Son both have authority over the Holy Spirit since He is sent by both the Father and the Son as one principle (John 15:26; John 16:7).
It has to be stressed that the Holy Spirit has to be understood as being sent by the Father and the Son, otherwise - if the Holy Spirit is sent by the Father alone - there would be no real distinction between the Son and the Holy Spirit and one would absorb the other. Wherefore, we could not really speak about a Trinity: this is a problem in Eastern Orthodox theology.
In terms of God being love, this can be understood as: the Son comes from the Father and both love each other. The Son does not only receive the love of the Father but also loves the Father. Therefore the Holy Spirit - the shared love - proceeds from both.
In conclusion, we have established the following:
a) that if we believe in a God who is love, then we would have to accept the Triune God as professed by the Christian religion
b) that if we wish to truly follow the Triune God, we must follow Catholicism which - unlike its sister Church - has preserved and taught through the ages the correct understanding of the relationship between the three persons of the Triune God.