God does NOT work through all religions. The Bible gives repeated warnings of false religions and false worship. Paul wrote concerning those who worship idols "The things which the nations sacrifice they sacrifice to demons and not to God, and I do not want you to become sharers with the demons" (1 Corinthians 10:20)
Jesus said "Nevertheless, the hour is coming, and it is now, when the true worshipers will worship the Father with spirit and truth, for, indeed, the Father is looking for suchlike ones to worship him. God is a Spirit, and those worshiping him must worship with spirit and truth." (John 4:23,24)
These verses show:
1. there are true worshipers (and by extension, false worship)
2. God requires worship based on truth.
3. God is very interested in those who worship him.
When the Israelites worshipped the calf Aaron made, Jehovah destroyed them. Time and again, Jehovah disciplined his people when they turned to false worship. False worship is ultimately given to demons and not to God.
Jesus showed that people of his day who believed they were worshipers of God were actually servants of Satan.
"You are from your father the Devil, and you wish to do the desires of your father. That one was a manslayer when he began, and he did not stand fast in the truth, because truth is not in him. When he speaks the lie, he speaks according to his own disposition, because he is a liar and the father of [the lie]. Because I, on the other hand, tell the truth, your do not believe me. Who of you convicts me of sin? If I speak truth, why is it you do not believe me? He that is from God listens to the sayings of God. This is why you do not listen, because you are not from God.” (John 8:44-47)
We need to find the Truth in order to please God and worship him acceptably. Saying God would accept any worship is as illogical as saying an employer would accept any kind of work we do for him. Good intentions are necessary but not enough. We need to find the truth and hold fast to it.
Let me see if I can explain myself better.
It is clear that idol worship is forbidden in the Bible. As are many other things. However, it is unfair to judge someone based on laws given to another people. The law of Moses and the Ten Commandments were given to the children of Israel. The children of Israel were God's people. They knew who he was and knew what he expected of them. For them to turn around and start worshipping some golden calf was completely inexcusable. "Where much is given, much is required."
We cannot judge someone without knowing what truth they already know and believe. It is true that we must find the truth and hold fast to it. Self righteously condemning other people because we think we have more truth than them is not acceptable. That is why we are taught to beware of false worship. There are many who claim to worship God just because they are members of this or that church. True discipleship is not based on the creeds one ascribes to. It is based on what one does. "Not every man that saith "Lord, Lord" shall enter into my Father's kingdom, but he that doeth the will of my Father who is in heaven." What is the will of our Father? That we go about doing good.
Everyone is given a portion of God's light. Such is obvious when we look at the common knowledge of right and wrong that can be found in any religion, race or culture. As you accept light and knowledge, God gives you more. We are taught line upon line, precept upon precept. The light we have grows brighter and brighter until the perfect day. I can assure you that God will accept without reservation the good done by all people be they Jews, Christians, Buddhists, Muslims, Hindus, Atheists or any other type. As an example. I believe 100% that my church is the restoration of the one originally set up by Christ while he was on the earth. However, I am willing to bet there are many "Good Mormons" who will have a serious wake up call when the judgement day arrives. They will wonder why someone who wasn't even a member of a church, let alone the "correct" church is going to heaven and they aren't. "But God! We were members of your Church!
We're supposed to be the ones going to heaven!" Jesus vividly described what will happen in the NT:
41 Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels:
42 For I was an hungred, and ye gave me no meat: I was thirsty, and ye gave me no drink:
43 I was a stranger, and ye took me not in: naked, and ye clothed me not: sick, and in prison, and ye visited me not.
44 Then shall they also answer him, saying, Lord, when saw we thee an hungred, or athirst, or a stranger, or naked, or sick, or in prison, and did not minister unto thee?
45 Then shall he answer them, saying, Verily I say unto you, Inasmuch as ye did it not to one of the least of these, ye did it not to me.
46 And these shall go away into everlasting punishment: but the righteous into life eternal.