Soandso
ᛋᛏᚨᚾᛞ ᛋᚢᚱᛖ
I can't answer the questions since I'm a life-long Christian with more fath and conviction than ever, but I do offer a relevant comment.
As others have suggested, this survey suspiciously puts the number one blame on rejection of the LGBT culture we now live in. Although that's reasonably likely for a small percentage of the population, there are a multitude of significant reasons noted by others here and various, better studies.
Answers in Genesis contracted an excellent third-party study on the subject and followed up with a book and some videos. It doesn't negate the alleged Bible contradictions, Christian hypocrisy behavior, or cultural opposing moral standards, but it does conclude another reason for youth under age 25 leaving the faith of their upbringing. Through various essay questions, the issue of evolution vs creationism consistently ranked number one on the list. This shouldn't be surprising since it affects everyone's world view, not just members of the LGBT community.
These surveyed kids, all raised in a Christian home environment, had their 6-day Genesis creation account attacked by the public school system, museums, media, and culture since early childhood - starting pre-grade school with the plethora of kiddies' dinosaur books. By high school and college, they succumbed to the powerful influence and embraced evolutionary theory. While I'd accuse their misguidance on lack of proper Christian apologetics teaching, the results are logical. Genesis is the foundation of the Christian faith. If it's undermined, the whole Bible's authority is undermined, and once that's done, one's faith is vulnerable to any number of attacks that seemingly refute it.
Although there are studies (and a lot of testimonies from converted atheists) showing that pain, suffering, and evil in the world is the number one cause of rejecting God, I do believe that the teaching of evolutionary theory in the public school system and society in general has been more effective at giving people freedom from religion than any other cause. It's not only created the popular misconception of the Bible opposing science, but has opened up the door (by dismissing Genesis and undermining the entire Bible's authority) to complete moral relativism. Thus, people today are able to conveniently use science as an excuse to exercise their own preferred moral values. How much easier it is to exercise one's pursuit of self interest and pleasure if there's no accountability to God and his objective standards.
I'll summarize with this. Choosing or rejecting Christianity is a matter of the heart, not the evidence. If one wants to explore the faith with an open mind, or defend the faith when challenged with cultural objections, there's an abundance of evidence supporting the Bible as 'the" authoritative source. But for the those wanting to serve oneself over God and others, there's also abundant material to justify such a position. In the end, the truth will be revealed regardless of the unanswered questions, counter culture standards, or inadequate behavior of Christians. Like most humans throughout world history, I believe there will be consequences to our choices in this life with a judgement day to face. Personally, I take immense joy and comfort in embracing my Creator, Lord, and Savior. I want the gift of love and grace that Jesus offers and the glorious new world, body, and eternal life to look forward to.
I'd be curious to know if you practice a different version of Christianity now than you did in the past. Have you always been a member of the denomination you currently practice in?