Ravi Zacharias has spent the better part of his life answering questions about Christianity.

The 73-year-old Christian apologist, who is known around the world for answering skeptics, gave his life to Jesus Christ at 17 years old on the verge of suicide, and for 47 years since he has been an itinerant speaker traveling the world defending the faith.

“I have come to the conclusion that it’s harder to find logic in life if there is no God," said Zacharias, the author of "The Logic of God," a book with 52 devotions for the heart and the mind, to Fox News.

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The founder of Ravi Zacharias International Ministries (RZIM), which has speakers engaging in apologetics at college campuses and forums across the world, says there is always a questioner behind every question, and that questions have changed dramatically since he started.

Ravi Zacharias, the founder of Ravi Zacharias International Ministries and noted Christian apologist, speaks at Princeton University on "Why I Am Not An Atheist." (RZIM)

"We have progressed immensely in our capacity to communicate, in our capacity to digitize everything, but oftentimes what is happening is we are living in front of a screen and missing out in relationships, and so the questions are getting larger and larger and the soul is getting emptier and emptier,” he said of the current generation.

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When Zacharias began speaking years ago, apologetics was heavily focused on debates like creation versus evolution and questioning of the authority of the Bible.

"Basically, they were questions to challenge the very notion of God’s existence," he said, "but now the questions are more existential."

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Young teens, bombarded with social media, are asking if their life is even worth living, but Zacharias, who himself asked that critical question as a teen, said all questions hang on one thread.

Ravi Zacharias answers a student's question at the University of Pennsylvania. (RZIM)

"All the questions you ask can only be answered after you have found the answer to the first question: Why you actually exist," he noted. "And when you find that that relationship with God through Jesus Christ, as I believe, then all the other questions are justified and the answers are forthcoming."

In addition to meaning, RZIM hears questions about sexuality, in some form, at every forum.

“Sexuality is the toughest one to deal with," Zacharias conceded, "but let’s remember it this way. It’s a gift, but it’s a gift that has parameters. It is possible to break it. It is possible to find fulfillment in it."

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The Christian scholar points to when people say things to him such as, "If two people really love each other, that’s all that really counts."

"Well, then I ask 'Why did you leave it at two? Why did you qualify it by love?'" he adds. "You’re already setting boundaries that sexuality is not without boundaries, so as a follower of Jesus Christ, I take His boundaries as the guidelines to enjoy the gift with responsibility, otherwise you can break it.”

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But even within the walls of the church, Zacharias noted, there are many who don't have the right answers, leading to a decline in some denominations.

“Some of the mainliners have lost numbers and they should’ve lost numbers because they lost the message," he said.  "If you’ve lost the real gospel, people are going to say, ‘Why am I coming here? Is this an ethical society or a feel-good moment on Sunday morning?’ but the evangelicals have grown in numbers."

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He added: "Some of the churches that are biggest and most packed are those where the gospel message of Jesus Christ is being given to the young and to those who are even thinking seriously about what life is all about."