Who has fashioned a god or cast an idol to no profit? (Isaiah 44:10)
The people in A.A. are doing the best they can with what they have been taught.
This is what they are NOT taught:
For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures, and that He appeared to Cephas, then to the twelve. (1 Corinthians 15:3-5)
This is what they are NOT taught:
Jesus said to him, “I am the way and the truth and the life; no one comes to the Father but through Me.” (John 14:6)
This is what A.A. people ARE taught about “god”:
[The alcoholic] “may choose to think of his Inner Self, the miracle of growth, a tree, man’s wonderment at the physical universe, the structure of the atom, or mere mathematical infinity. Whatever form is visualized, the neophyte is taught that he must rely on it and, in his own way, to pray to the Power for strength.” 
The above definition of “god” comes from official A.A. literature.
In A.A. one often hears about alcoholism being a “spiritual disease.” It is more accurate to see Alcoholics Anonymous as the spiritual disease, because it has pointed millions away from the Christ of the Bible, and watered down the beliefs of the Christians who have become members.
A.A. is powerful in terms of public relations, weak in terms of treatment effectiveness, and unholy in its understanding of “god.” But the A.A. people don’t know this. They are working to gain or maintain sobriety, and they are doing what they have learned to do.
Many of us are sober because of Christ. We go to church. Some of us attend Bible based fellowship groups like The Most Excellent Way. This claim that A.A. is the most effective way/only way to get sober is a lie. The sad truth is, most do not get sober through A.A. Far worse, every person who designs an A.A. higher power of their own understanding will end up in hell.
So, what can we do? Well, when we speak with out A.A. friends, we can share the gospel message. They may have never heard it before. We can do this in many ways, but let’s directly proclaim the Good News:
How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard? And how will they hear without a preacher? (Romans 10:14)
One last thought. In A.A. there are people who call “Christ” their higher power, and with some it is the biblical Christ. But Christians in A.A. rationalize that it is okay for someone to worship a higher power for a time because that person will supposedly come to Christ sooner or later. This rationalization allows the Christian to stay in A.A., for A.A. itself has become an idol.
Very few find the biblical Christ in the A.A. religion.
The Bible is clear that the times of ignorance have passed. Paul, speaking to men in a city full of idols:
“Being then the children of God, we ought not to think that the Divine Nature is like gold or silver or stone, an image formed by the art and thought of man.
“Therefore having overlooked the times of ignorance, God is now declaring to men that all people everywhere should repent,
because He has fixed a day in which He will judge the world in righteousness through a Man whom He has appointed, having furnished proof to all men by raising Him from the dead.”
Now when they heard of the resurrection of the dead, some began to sneer, but others said, “We shall hear you again concerning this.”
So Paul went out of their midst.
But some men joined him and believed, among whom also were Dionysius the Areopagite and a woman named Damaris and others with them. (Acts 17:28-34)
Some sneered; some wanted to hear more; and some were saved.
But all heard. Can we do any less for our friends in Alcoholics Anonymous?
[Bonus: This small booklet about A.A.’s unholy foundations can be read online HERE… ]
1. Jack Alexander, “Alcoholics Anonymous: Freed Slaves of Drink, Now They Free Others” (Saturday Evening Post, March 1, 1941). According to the A.A. website, A.A. World Services publishes the article in pamphlet format and sells about 22,000 of them each year; http://www.aa.org/lang/en/subpage.cfm?page=472.