Life almost definitely exists elsewhere, and this is coming from a religious person. The number of star/planet combinations out there virtually guarantees it mathematically. The problem is that space is too large and vast and the speed of light too "slow" to be able to reliably "scan" the universe fast enough to find life.

Two scenarios (at least):

1. God exists and specifically seeded life on Earth.

Even if this is the case there is still no reason meteorites couldn't carry microbes from Earth to Mars. It doesn't seem like God cares about quarantining life to earth, seeing as we made it to the moon.

Also, why bother making a universe so mindbogglingly huge and vast only to put life on a single planet? Makes more sense for God to seed countless planets out there with life. And indeed there are a few verses in the Bible that imply Earth is not God's only creation.

2. God does not exist and life emerged naturally.

If this is the case then that means life can emerge naturally somewhere else with identical conditions, and given the number of stars/planets/time elapsed, this seems like it could be a high probability (hard to know, though, without understanding exactly how life emerges).