1 - Q. How do we know God and/or Jesus really exist if we can't see them?
A. - By looking at the evidence for good and evil in the world (and in our own heart) that corroborates with the struggle human beings have, as described in the Bible. Can you see the wind, air, gravity, your brain, microwaves, radio waves, etc. without instruments? Without instruments, how do we know gravity exists? We see evidence for gravity here on earth and with certain airplanes and spacecraft that experience zero-g's. Christians believe what the Bible tells us; that it is impossible for God to lie. The Holy Spirit helps us get to know God and the Bible. Jesus was the only person who died, rose from the dead and ascended into heaven in view of hundreds of witnesses.
2 - Q. - Don't all roads/paths lead to God/heaven?
A. - This reminds me of a joke I heard while vacationing in Oregon, "All roads lead to Crater Lake." Maybe it's true in Oregon folklore but think about the real world; do all roads lead to your house? Can you get to your favorite website by typing in gibberish.com? Can you get on a bus heading to Los Angeles, California and expect to step off in New York City? Christianity is exclusive. It requires faith in Jesus Christ alone for salvation. Jesus is "saving" you from an eternity in Hell; a lake of burning sulfur fire where the flame never goes out and the worm never dies. A place of eternal torment where you'll always be thirsty but there's no water.
3 - Q. - How does someone "believe" in Jesus for salvation?
A. - It's not like believing in the word 'believe,' fairies, or pixies. Imagine being on the Titanic (back in 1912) and it has just struck an iceberg and is sinking into the freezing cold waters of the North Atlantic Ocean. You see several lifeboats and one has the name, "Jesus Christ." You see other lifeboats; one is called "good works," "money," "prosperity," "party-boat," etc. You see boats with names of other religions; Buddha, Islam, Mormonism, Jehovah's Witness, etc. but you remember that someone told you "Jesus saves," so you head to the lifeboat with his name on it. As you get closer you see Jesus beckoning you to come to him. He is there to comfort you. Even though you're hungry, wet, cold uncomfortable and scared you are so glad you chose that boat because the other ones have holes in them and are sinking into the water. You look back at the Titanic and realize it would have been futile to try and cling to it because it is sinking fast and within minutes it is almost out of sight.
Our earthly bodies will end in death, returning to the dust while our spirit goes to be with Jesus or cast into Hell. Ten out of ten people die. It is silly to try and put all our hopes and dreams in this life alone. Our only hope is to be "all in" with Jesus.
You look around at the people next to you on the lifeboat and realize your skin color, bank account, gender, political preference, physical abilities, etc. don't matter to Jesus. You could be an Olympic swimmer and die of hypothermia if you tried to save yourself.
4. - Q. - Aren't all religions basically the same?
A. - Not according to the Bible. There's one true God and any other person claiming to be "God" is a demon. Just because it looks and sounds like the "real deal," (Christianity) it is a counterfeit. Think of counterfeiters who try and pass off their fake currency as real money, the closer it looks and feels like a "real" bill, the easier it is to fool the masses. If someone offered you a genuine hundred dollar bill or a counterfeit, which one would you rather have when it is being closely examined? Study the Bible so you can easily discern truth from error.
5. - Q. -How can I tell if I've found the real, living God?
A. - God reveals himself to us in the Bible. He's not who we "imagine" him to be, that's called idolatry, making up a god to suit our own wishes and desires. God tells us who He is in the Bible. If we seek him, we'll find him, if we seek him with all our heart.
6. - Q. -How can we trust the Bible since it was written by man?
A. - The same way you can trust anything written by man, test it and see if it's true. There are books on every conceivable subject written by man. That doesn't mean that we will never go to a doctor, walk across a bridge, get on a train or ride in an elevator. A book that tells someone how to build an airplane and manuals that tell pilots how to fly and a mechanic how to repair the plane are all written by man but that doesn't keep people from flying. The Bible is a "manual" that teaches us how to know God and get along with other humans.
The Bible writers were all inspired by God to write down everything they wrote. It's like sending a text message, email or letter to someone and people start accusing your pen, computer or cell phone of making up words and writing them down. God used men as his paper and ink to write the Bible.
7. - Q. I thought Jesus was all about love, isn't it unloving to tell me my lifestyle is wrong and I'm heading to Hell?
A. - If you see a two-year-old taking their toys out to play on a busy road, is it unloving to warn that two-year-old of the danger and try and get them to safety? We are the two-year-olds and God is sending out Christian's to warn other toddlers that their life-style has serious, eternal consequences. God even tells Christian's that we will be held accountable for your punishment if we don't warn you first.
Important side note: The Bible warns us that even if an angel from heaven tries to tell us a "different gospel" or how to be "saved" apart from Jesus, we are not to believe them.
For more answers:
What is Christianity and what do Christians believe?