"The One True God."
http://ichthys.com 
Question:   
In light of the recent events, I have had people asking me if Islam worships the one true God. What would be your answer?
Response:
Let me try to answer your question in this way. When Jesus had His extended conversation with the Samaritan woman and she inquired whether Mt. Gerazim or Mt. Zion was the proper place to worship God (and there is clearly an implied desire in her question to find justification for the practice of which she was a part), Jesus replied "You [Samaritans] worship what you do not know; we worship what we know, because salvation is from the Jews" (Jn.4:22). This is most significant, for the Samaritan religion was very close to that of Israel in form, and was established, you may recall, by the peoples imported into the Northern Kingdom area after the Assyrian conquest specifically to placate the God of Israel, "the One true God" (2Kng.17). There still exists today a copy of the "Samaritan Pentateuch", the first five books of the Bible translated into Aramaic and used by this religion. So it is clear that this group deliberately attempted to worship the same God as Israel with the same sacred texts and in, as far as we can tell, a similar way - just not in God's very specific way. Jesus is very particular in saying that they "did not know what they were worshiping", and goes on to explain to the woman the true way of life: salvation through faith in Himself, the Messiah (of whom she had heard, but in whom she and her fellow Samaritans did not yet have a saving faith: Jn.4:26; cf.4:42). We can take this a step further and apply this to those Jews who are not part of the believing remnant that exists in every generation of the Church (Rom.11:5): Paul, whose Jewish credentials were second to none (Rom.11:5; Phil.3:4-6), tells us that those of his countrymen who do not accept Jesus Christ "have a zeal for God [the One true God], but not according to true knowledge" (Rom.10:2). The word I translate "true knowledge" here is the Greek epignosis which means not just knowledge, but knowledge directed at something, and, in scripture, specifically knowledge that includes recognition or acceptance [of God and His truth]: unbelieving Israel is aware of the One true God, but is unwilling to approach Him on His terms, namely, faith in Jesus Christ. Jesus told us that the way was steep and narrow which leads to eternal life (Matt.7:14), and that He is the only Way (Jn.14:6). Every human being who attains adulthood and normal mental competency becomes aware of the existence of the God (even if only to reject this most critical bit of natural revelation later in life: Rom.1:19-20; cf. Ps.19). But what does the scripture say? "For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened" (Rom.2:21 – NIV). Many religions, philosophies, cults etc. proclaim and, after a fashion, may actually believe in a single, universal God. They are not for this reason saved, for they have not seen fit to respond to Him His way through Jesus Christ (so as to worship Him in His way, in gratitude for the salvation He has wrought in Jesus Christ). Even the demons understand that there is only one God, and shudder at their future prospects as a result of this knowledge (Jas.2:19). Such knowledge does not save – salvation comes as a result of obeying God and putting faith in the One in whom salvation alone resides, our Lord Jesus Christ. Therefore the issue is not only whether the God people focus on is true, but whether the worship is true. This is the very point with which Jesus concludes His conversation with the Samaritan woman (the place we began this discussion):         
But the hour is coming, and in fact has already arrived, when the true worshipers [of God] will worship the Father spiritually [i.e., our spirit responding to His Spirit] and truthfully [i.e., our heart responding to His truth]. Indeed, it is just such worshipers that the Father is seeking. For God is spirit, and those who worship Him must do so spiritually and truthfully.
John 4:23-24 
So then only those who worship God the Father "in spirit and in truth" are acceptable to Him. That is to say, no one can dictate to God how He will be worshiped, for He will be genuinely worshiped only in the way that He finds acceptable – anything else is not really worship at all but mere human self-righteous activity. The sole acceptable and godly way to worship Him is clearly the Way, that is, through faith and faithful following of our Lord Jesus Christ, who is the Truth and the only way to eternal life (Jn.14:6). Clearly, it is not only Muslims and non-believing Jews and members of all manner of religions and philosophies and sects and what have you who will be found wanting by God on that Great Day of Judgment for failing to appreciate the ineffable gift of His Son. How many are there who belong to Christian groups and denominations or otherwise profess association with the like who possess no genuine faith in Christ or faith so feeble that it is in danger of being swept away at the first hint of tribulation? The fact that their organizations espoused Christ but they themselves did not believe (or abandoned their faith) will not be accounted as true worship; and on the other hand, any and all in other groups who do turn from their unbelief to the Living God through Jesus Christ will not be hindered from salvation because of their prior lack of true worship. For, as He says of Israel, "if they do not persist in their unbelief, they will be grafted in again" (Rom.11:23). Hard times are coming for the Church, and for the world. It is prophesied that many will fall away in this time of testing to come, an expected if heart-wrenching outcome of the lukewarm nature of this last, "Laodicean" generation of the Church (2Thes.2:3; 1Tim.4:1; Rev.3:14-16 – a topic covered in the "Coming Tribulation" series). It seems to me that all of us who do indeed truly worship the One true God by approaching Him through faith in His beloved Son would all do well to remember Paul's caveat to the Corinthians following his description of the failure of the Exodus generation:

These things all happened [to the Exodus generation] by way of an example so that we might not lust after what is evil as they did. Don't practice idolatry, as some of them did (as the scripture says "the people sat down to eat and got up to frolic”). Don't fornicate, as some of them did, and 23,000 of them fell dead in a single day. And let's not put the Lord to the test, as some of them did, and were killed by snakes. And don't complain, as some of them did, and were killed by the destroying angel. All these things happened to them to give us an example, and have been written in scripture to warn us as we confront history's final epoch.  So let whoever thinks he's standing firm be careful not to fall!
1st Corinthians 10:6-12
 
I hope this is a helpful response, 
Yours in Christ, 
Bob Luginbill 
http://ichthys.com