People who do not believe in God don't want any proof. You can't even talk to them. They don't want to hear it.
So here's what you do:
Most people who do not believe in God believe in evolution. Show them that evolution cannot possibly explain everything. While there can be no actual proof of God (short of seeing Him in person some day), it IS possible to disprove evolution. Find a few counterexamples, make your friends reconsider their basic assumptions, and they may reconsider the possibility of God.
As Spock said on Star Trek, "If you eliminate the impossible, then whatever remains, however improbable, must be the truth."
For Example... Ask your friend why giraffes are so tall. This is the evolutionist's centerpiece example in their narrative. They'll probably answer, "Because taller giraffes were able get to the high leaves during a drought. Survival of the fittest."
This book gives TEN reasons why that answer does NOT explain why giraffes are so tall. The most compelling one is this: Being tall did NOT give an advantage! A short giraffe could simply bend down and eat grass. We still have goats, horses, etc., which also did not die out.
The problem is that evolutionists DON'T give this fable any thought. They tell each other this anecdote, which lets them hang onto their belief in evolution, which they can use to justify their nonbelief in God.
Evolution Does Not Explain Everything Evolution can provide improvements, but it does not explain how things got started.
Consider vision. Could a single mutation have caused an eyeball (complete with a lens and a retina), an optic nerve that could keep all the pixels straight, and a brain with pattern recognition? All at once? Very unlikely.
These parts could not have arrived one at a time, either. An animal that was missing even one part would not have a system that almost worked; it would have a system that did not work at all. This dead-weight system would not have provided any advantage, and so would not have been carried forward until another mutation could provide the next part.
Remember, for the evolutionist, it's all random. They don't believe that there was an Inventor that could design the system, diagnose a problem, and make a correction.
Nor can evolution make gradual improvements to sneak up on these advances:
- INSTINCT: How can a baby's brain be hard-wired to know how to breathe, suck, and beat its heart? How did babies survive before these mutations? There's no time to learn these skills.
- DNA: Evolution could not even begin until DNA was up and running. The first cell with DNA needed to create that double-helix spiral structure. And it had to know how to specialize using that blueprint (become a finger? a heart valve?) And that first cell with DNA had to know how to replicate its DNA during a cell split, or it would be the LAST cell with DNA. One cell had to do all that?
- TWO SEXES: In the beginning, cells would split into two identical cells. Then there must have been TWO mutations in two different individual cells creating the first male and the first female. Two COMPLEMENTARY mutations! In the same place and at the same time! What Luck!
- LIFE ITSELF: There was no primordial ooze. Even if the right chemicals happened to exist in one place, and even if a lucky bolt of lightning struck that pool, the simplest cell is just too complicated to have happened accidentally and randomly.
Show your nonbelieving friends that evolution does not explain it all. Make them reconsider their assumptions. Make them reconsider the possibility of God.