Doubts are necessary to strengthen our Faith.
When God asked us to love Him, He didn’t want to force us in anyway. He wanted us to choose freely whether to love Him or not.
That’s why He allows doubts to creep in our minds from time to time. They help us to get to know Him better. We ask questions, we learn from the answers we find, we get closer to Him. Just like any other relationship; the more you know about the other person the closer you get to him or her.
Of course, too much doubt can make us lose our Faith altogether. The devil would be glad of that. That’s why he plays with our doubts and adds more to them; in order to confuse us and lead us astray.
We must learn to control our doubts, and use them to our benefit not the devil’s. When we have doubts about our Faith, we should not fear them but we should pray for guidance from our Lord.
"I believe, Lord; help my unbelief." Mark 9:24.