Is doubt OK?
God is OK with doubt, He gives us the ability to think, so doubt about what we are told to think is OK - as long as that doubt leads to seeking the Truth. If you truly seek the Truth it will be found, resulting in re-thinking what you thought you knew, resulting in a changed mind, a mind that now believes the Gospel.
When doubt leads to ignoring rather than seeking, people die in their sin and go to hell, as the Word says, "My people are destroyed for lack of knowledge."
Pride keeps men from seeking the Truth, pride keeps them from humbling saying, "maybe I don't know as much as I think I know." For some, their pride won't allow them to seek the Truth because they would have to eventually say, "I was wrong, my thinking was wrong." The Truth is like math, there is only one right answer. Math doesn't need to argue with you that 9x9 isn't 82; it knows it is 81; if you seek the truth long enough you will find out it is 81. In the same way, the Truth is the Truth, seek it and you'll find it.
Matthew 7:7 "Ask, and it will be given to you; seek, and you will find; knock, and it will be opened to you.
John 20:24-28 Now Thomas, one of the Twelve, called the Twin, was not with them when Jesus came. So the other disciples told him, "We have seen the Lord." But he said to them, "Unless I see in his hands the mark of the nails, and place my finger into the mark of the nails, and place my hand into his side, I will never believe." Eight days later, his disciples were inside again, and Thomas was with them. Although the doors were locked, Jesus came and stood among them and said, "Peace be with you." Then he said to Thomas, "Put your finger here, and see my hands; and put out your hand, and place it in my side. Do not disbelieve, but believe." Thomas answered him, "My Lord and my God!"
Hosea 4:6 My people are destroyed for lack of knowledge; because you have rejected knowledge, I reject you from being a priest to me. And since you have forgotten the law of your God, I also will forget your children.