An Effective Witness
The vast majority of the world's people are religious, and at the very deepest level of their being, it is their religion that governs them. We can't even begin to understand them without knowing of their religions.
We Christians know that Jesus commanded us to make disciples of all nations (Matt. 28:18–20). We also know that he commanded us to love our neighbors as ourselves (Mark 12:33) and to follow the Golden Rule (Matt. 7:12), treating others the way we want to be treated.
Suppose my neighbor already believes in a god of grace (as many Hindus and Buddhists do), and I assume he knows only a god of law, and our conversation reveals my lack of understanding to him. In other words, he believes his god forgives sins out of sheer love, but I assume his god will only punish sins and not forgive them. Not only will I fail to show him the courtesy of my understanding, but I will fail miserably in my role as an evangelist.
Surveys show that many people in the west these days have a belief in a God, but are not strong adherents of a particular religion. Their God has some characteristics of the Christian God (good, powerful, loving) but few of the 'tougher' characteristics (high ethical standards, interfering).
Other people may talk about the divine presence within all people.
It is hard to assess such beliefs, because they offer little beyond personal faith as a reason to believe. However they do not satisfy the criteria that God has communicated to many people, nor do their gods have much of the tough realism required by other criteria. It seems that most of these believers claim no more than subjective "truth" for their belief.
If I study his religion, I may find that what he really wants to hear is not about grace but history – whether God ever really entered history. That will make my witness more effective.
As we have seen, Judaism, Christianity, Islam, Baha'i, Zoroastrianism and Sikhism all believe in one God. These Gods meet most of the above criteria - they are creators, have ethics, are 'personal' and reveal themselves. They have a lot in common, but they each place different requirements on those who believe. Christianity, Islam and Judaism are generally considered by historians to have promoted the rise of modern science.
However only Christianity and Islam have really become 'world' religions, believed by a significant percentage of people, so belief in the others is more problematic.
Hinduism, some other Asian religions (Jainism and perhaps Shinto), and many local or tribal religions (for example, ancient Greek, Roman or Norse, and animistic religions today), believe in many gods, or a God or spiritual force revealed through many aspects which may appear as separate gods.
These Gods don't satisfy the criteria so well - some are ethical but some are not, they are not always seen as the great creators of the universe and they appear to be less connected to the human race. Philospher Mortimor Adler and physicist-theologian John Polkinghorne both suggest that some aspects of eastern religions (and probably many polytheistic religions as well) are incompatible with the scientific method - for example, often their worlds are chaotic or even an illusion, lacking the hard reality and physical laws we are familiar with, and their logic can allow mutually exclusive things to both be true, which does not fit with modern science.
Of these religions, only Hinduism can really claim to be a "world" religion.
Less knowable gods
The Buddha did not teach much about God, the taoic religions (Confucianism, Taosim, and perhaps Shinto) also stress ethics and philosophy rather than faith in a god. Thus these, also, do not meet many of the criteria we have suggested - it is hard to see a ceator god among them, nor a god interested in people as individuals. Only Buddhism can claim to be a world religion.
These beliefs may be more attractive to those who don't believe that the evidence points to the existence of a creator God.
Roll your own gods
Surveys show that many people in the west these days have a belief in a God, but are not strong adherents of a particular religion. Their God has some characteristics of the Christian God (good, powerful, loving) but few of the 'tougher' characteristics (high ethical standards, interfering). (1)
I spotted D.A.Carson’s summary of the teaching of the Bible. I believe it comes in at around 221 words. Here it goes:
God is the sovereign, transcendent and personal God who has made the universe, including us, his image-bearers. Our misery lies in our rebellion, our alienation from God, which, despite his forbearance, attracts his implacable wrath.
But God, precisely because love is of the very essence of his character, takes the initiative and prepared for the coming of his own Son by raising up a people who, by covenantal stipulations, temple worship, systems of sacrifice and of priesthood, by kings and by prophets, are taught something of what God is planning and what he expects.
In the fullness of time his Son comes and takes on human nature. He comes not, in the first instance, to judge but to save: he dies the death of his people, rises from the grave and, in returning to his heavenly Father, bequeaths the Holy Spirit as the down payment and guarantee of the ultimate gift he has secured for them—an eternity of bliss in the presence of God himself, in a new heaven and a new earth, the home of righteousness.
The only alternative is to be shut out from the presence of this God forever, in the torments of hell. What men and women must do, before it is too late, is repent and trust Christ; the alternative is to disobey the gospel.