Why should we believe in Jesus?
Now that is a very good question, and one that is not always easy to answer. But here is my answer.
Before I became a Christian, I looked at many of the worlds religions, I have relatives who are Sikhs, friends who are pagan, family members who are Atheist, I would read books on Islam, Hinduism, Buddhism, and a whole host of other faiths.
During this reading I found something that was certainly very attractive, they all promised eternal life as long as I worked hard enough for it and was good enough for it.
However, this left a problem within me. I realized that for every good thing I did, I would do something bad. Often I would inadvertently do 2 or more things bad for every good thing I did. If I was too keep a record of everything I did, both good and bad, it would be almost impossible for me to tip the scales to a good balance. I based this on knowledge of who I was (and still am in many respects). I was greedy, self centered, suicidal, filled with hatred and envy, and a whole bunch of other things.
To make right on my many sins was going to take a long long time, and while I was trying to do right I would more than likely forget and slip back and do wrong, therefore adding more negativity to my balance (this by the way is referred to as a works salvation).
At that point some friends of mine invited me to a christian church, where I found a different belief system, one that does not require me to work for my salvation, but one that gives me salvation for free. By believing in Jesus, all my sins could be forgiven, this is a total reversal from other faiths I looked at.
This is what led me to Christ, the idea that no matter how bad I had been, I could be forgiven.
Now do not get me wrong, Christians are still expected to do good works, that is in the manner of loving your neighbor as yourself. Also the works a Christian does are in the manner of showing how his faith is working within him (referred to as the fruit of the Spirit). But a Christians salvation is not based on his works but in his faith in God.
So why believe in Jesus? Simply put, Christians have a hope of eternal life that is not based earning our way into heaven, but is instead based on Loving Jesus and being loved BY God.