Can someone go to Heaven if they trust in Christ, but mistakenly believe that their baptism contributes to their salvation?

There are those who teach that you must trust Christ and in certain rituals. Some of the people in these churches are saved—not because they believe what their church teaches, but in spite of it—because in reality they are trusting in Christ alone for their righteousness and not putting any confidence in their own righteous deeds to make them acceptable to God.

In the same way, there are some in the [group you are asking about] who are saved, not because they are trusting in Christ and their obedient work of baptism, but because they are looking to Christ alone to make them right with God.

As a Baptist, I can attest that there are people in Baptist churches who, though they are taught otherwise, are trusting in Christ plus their response at the end of a service, or in their baptism, or church attendance, or good life. At funerals you will hear them say, "If anyone is going to Heaven, he/she is, because he/she lived such a good life." And they'll say this despite decades of giving the right answer in Sunday School when asked if people are saved by grace or by works.

Whenever salvation is couched in terms of "Christ plus ____," it doesn't matter what's in the blank, for eventually that becomes the emphasis because that's a work that we do. And then our confidence lies in the fact that we have done "it," whatever "it" is. Even though it may be taught that Christ's work is 99.9% of that equation, the emphasis will be on the .1% that's in our power, and that results in relying upon our obedience in a righteous work. But the Bible says that our righteousnesses (i.e., our individual acts of righteousness, such as obedience to baptism) are as filthy rags in God's sight, at least in terms of impressing Him that He should let us into Heaven. We should do acts of righteousness (such as be baptized after we believe), and there is a sense God is pleased with our acts of righteousness, for He certainly does not want us to disobey and do acts of unrighteousness. But these acts of righteousness do not cause God to open the door of Heaven for us.

So in one sense, salvation is by works—but not yours! Jesus earned Heaven. He fully kept the Law and never broke the Law. His righteous life on earth earned eternal life in Heaven with God. He's the only One who ever earned Heaven. And our entrance into Heaven is secured by being united with Him by faith. We believe "into" [and not just "in"] Christ, and thus are given credit for having lived His righteous life. On the Cross, He got credit for having lived my life, which is why He received the wrath of God (that I deserved).

The bottom line is that it's all about union with Christ. Are we united with Him by faith, or are we united with Him by a work, such as baptism? Baptism is a symbol of that faith in Christ's righteousness—an important symbol—but a symbol nonetheless. If anyone believes their baptism establishes part of their righteousness with God, then they are believing in another Gospel, a Gospel that has had something besides Christ's righeousness added to it.

So you are asking me something that you've probably known the answer to all along. You are really asking that if someone is sincere, will they go to Heaven, even if they are sincerely wrong. If someone has been taught that trusting in Christ plus participating in a ritual or biblical practice will save them, and they sincerely believe this, then they are trusting in a false Gospel. Even though it is closer to the true Gospel in many ways than, say, Islam or Buddhism, it is still not the true Gospel. It is a "Christ plus ____" Gospel.

But again, there are some in many groups who, despite what they are taught and maybe even what they express, are really trusting in Christ alone for salvation. Ultimately we don't know their hearts, and we let God sort that out. But we must affirm that only the true Gospel saves, and anyone who trusts in a false Gospel—however sincere—is not saved. I think it's time for you to come to terms with this: What is the Gospel? What does the Bible say is the only message that saves?