This is a great question and it is completely a matter of faith based on what is known about God through written records. This statement itself is a matter of faith, because it is easy to argue that the written record is nothing more than the words of people a long ago. But this is where the faith comes in.
If we look at the Christian Bible, there are many passage that speak of the love of God. I suggest that you start there and see how these texts speak to your heart. If you believe, then you have faith.
Also we can say that there is another way. This way is based on our experiences or the experiences of others. For instance, you might hear a testimony of God's goodness and this testimony might move you to faith. I will attach three short articles on what the Bible says about God's goodness.