I had a really great conversation with someone in my family last night, and it prompted me to clarify something. This may get a bit deep, but I'll try to be as clear as I can. It's also long, so proceed at your own risk.
All Christians, Evangelical, Mainline or Catholic proceed from a certain set of assumptions. Most Catholics, for example, don't make a "personal relationship with Jesus" a central part of their faith and practice. They experience God primarily through liturgy and sacrament and interpret Scripture within the context of not just the local parish community, but within the wider Catholic traditions of the last 1,500 years or so. Evangelicals, who centralize a personal, experiential relationship with Jesus and a clear, memorable "conversion experience" are horrified by what they regard as paganism by the Catholics, while Catholics are flabbergasted by arrogant, populist Evangelicalism. Both proceed from their own assumptions, which are based on their interpretation of - you guessed it - the Bible.
Let's take this a step further. All orthodox Christians assume the doctrinal truth of the Trinity. The Bible, however, does not directly teach trinitarian doctrine anywhere. It is an invention of the third and fourth centuries AD, arrived at as an interpretation of several passages, and it was by no means uncontested. The wording of the Nicene Creed reflects the controversy. It does not say "we believe in a trinitarian God," it says "we believe in one God," and then goes on to clarify the three persons.
So do we believe in one God or three gods? A Muslim would insist that we believe in three Gods, and if we equate the words "God" and "Allah" (and I would), then to an Muslim now we're engaging in idolatry. Explain it any way you want, and the result is the same.
The thing is, the Trinity rests on a bunch of assumptions of which most Christians are not aware. It is a product of a Greco-Roman way of ordering theology. Greek philosophy had no trouble distinguishing between distinct things, entities or identities while maintaining a cohesive unity. They saw it all around them, after all. A tree was both unity and multiplicity, a single thing made up of constituent parts that informed and defined it. The Greeks saw each person as a whole greater than the sum of his or her parts. Their pantheon of gods reflected this, as each individual deity was really no more than a reflection of an aspect of Divinity. When Christianity came along, the Greco-Roman world had no trouble at all with the concept of a trinitarian God because it had an epistemological framework ready-made.
But it goes even further than that. Greco-Roman society was rigidly structured, an orderly hierarchy into which each person fit in a specific place. The layers were somewhat permeable; one could move up the ladder, as it were, but only with the help of someone at the next level, which made the complex web of kinship and patronage critically important. Honor was found not in rising above one's station, but by fulfilling one's purpose in the social order to the best of one's ability. Paradoxically, a person who wanted to rise through the ranks would not do so through self promotion, but by strict attendance to the obligations appropriate to his or her rank. The idea of a well-ordered, eternally static Trinity made up of persons with distinct roles fit perfectly into Roman society (or was it a product of Roman society?).
The Trinity was not a universal concept though, not even for Christians. It was largely a doctrine of the Western Church, which quickly imposed the social order on the church, rigidly ordering it with pastors, priests, bishops, archbishops and so on, and on the Trinity, which it ordered neatly in terms of the Roman household: Father, Son and Spirit (wife). Although the official formulation recognized that all members were co-equal, the Church historically has framed the Trinity in subordinationist terms (Father, then Son, then Spirit).
The Eastern Church, however, made very different assumptions. It arose in a culture that did not order itself as rigidly and though it accepted the general hierarchy of the Western Church, it consistently pursued a more community-based daily practice. One might say that the Western Church emphasized the oneness of God, while the Eastern Church emphasized the threeness. This has had all sorts of implications for the way these two strands of the Church have organized themselves. We Evangelicals are a product of the Western Church and have inherited much of its theology and organization. Much what we believe about God, which we think comes directly from the Bible, is really based on a framework of Greek philosophical understanding. The salvation experience, a personal relationship with Jesus, conversion, the Trinity - all rely on the assumptions that Westerners bring to the table, and are not shared by much of the rest of the world.
Arab culture, for example, has arisen under very different circumstances. The geography and climate made cooperative effort critically important. Since resources were scarce, Arabs organized their society in tribes that were more flexible and mobile so they could easily relocate when circumstances demanded it. While there has always been a hierarchy, the tribal structure and the importance of cooperation made it much less nuanced. There was the Sheikh and his family, and then everybody else. There was little exploitation though, and so no need to form a more stratified social order. The difficult conditions under which life was lived demanded cohesiveness; oneness and unity were matters of life and death
Islam reflects this understanding. There is Allah and there is Muhammed, the Prophet of Allah. While Muhammed is revered above other men, he is not Allah. Islam emphasizes the oneness and singular importance of Allah, around which every other element is arranged. Arab Muslims have one God, complete in himself and in whom all mankind finds completeness and unity, and there is no societal framework for conceptualizing something like a Trinity. It's not that they're not intelligent enough to understand it, or that they don't want to understand it, but that it simply doesn't make the slightest bit of sense to them because they come to the table with a completely different set of assumptions. The fine distinctions Western Christians make between the persons of the Trinity sound like contradictory nonsense. Arab Muslims proceed from an extremely conservative interpretation of the Koran, which is read only in the original Arabic and only by men trained to do so; consequently, our formulation of doctrine by implication (rather than strict literal interpretation of Scripture) also doesn't work for them.
This is a very long post to say this: don't be too sure that the things you believe proceed directly from a clear, unadulterated understanding of Scriptural truth directly from God. God speaks to people in ways that they comprehend; if he wanted to reveal himself to an Arab, would he not do so in a language and culture that he could grasp? After all, the fact that you're Christian is largely because you were born in America (the heir of the Roman Empire) and that the Roman Empire adopted Christianity early on, and that happened because God revealed himself to Jews in first-century Palestine. If you are a Christian, it is mostly by virtue of your birth into the Western world. Were you born in Riyadh, Saudi Arabia, you would be Muslim. Were you born in India, or in much of Asia, you would be Buddhist. In neither case would much of what Christians believe make any sense to you no matter how carefully put.
Do you really want God to reach the world? The WHOLE world? Then you might have to release some of your hangups about how he does it. There are distortions in every belief system; God asks everyone to change something, Christian, Muslim, Buddhist or otherwise. Let God do things his way; don't impose your assumptions on it.