Getting back to the OP...
I think it's a fair point; I have made similar statements in the past, but to little avail. If there is a God, then I think most people on this forum would agree that, out of all the currently available choices, Christianity seems to have the most reasonable understanding of His nature. But Jesus did not preach advanced philosophical argumentation and complex metaphysics.
If Christian theology is correct, then we are made in His image. As beings made in His image, we should recognize His truth when we hear it. But if we have distorted our perception of truth through sin and hardness of heart, we will struggle to recognize His word. Thus the call to repentance and conversion of one's heart. If you are not willing to do this, you are wasting your time with Christianity, and Scripture will remain meaningless to you.
Even if loony denominations (or even other religions) make this same claim, this does not falsify it. If we have free will, then this freedom also extends to the realm of theological dishonesty. At the end of the day, we cling to the truth that our heart desires. If we desire evil, we will subscribe to evil beliefs/ideologies and, if God exists and is just, we will be judged and punished for our evil choices.
