A God worthy of complete trust must exhibit three qualities - Truth, Power, and Love.
In a perfect world, a child learns to trust and obey their parents. A parent has power over their child, teaches their child the truth, and shows unconditional love towards their child. It is these three qualities that lead a child to completely entrust their life into the hands of their parents.
However, each of these qualities, on their own, are not a good reason to trust someone. The government has power over a child, but they don't really love the child like a parent does. A school teacher may tell a child the truth, but a teacher has no real disciplinary power over the child. A child's best friend may show unconditional love, but really isn't yet interested in the truth, and has no power over him. Only when these three qualities - Truth, Power, Love - combine do we find it sensible for complete, absolute trust.
Just as a child entrusts their life to a parent, so too we must entrust our soul to God. But, not just any God - only a trustworthy God - a God who is Truthful, Powerful, and Loving. Power alone isn't enough to solicit trust, as even demonic activity can be quite powerful. A miracle alone is a poor reason to trust in something. If Christ had merely performed a few signs and wonders - it would not be enough to garner faith.
If Christ had only been a teacher of great truths, this too would be insufficient. Many different religious systems contain elements of truth about life, and have practical wisdom for it's followers. Just because someone tells you the truth doesn't mean you should trust them with your soul. If they have no power over you, and/or they don't love you - it renders the truth they tell you virtually meaningless - at least as far as your eternity is concerned.
Finally, if Christ had only exhibited a Mother Theresa-ish love, it would not have been enough. Cults are notorious for their relentless, welcoming love of new converts, but cults are decidely lacking in the truth department. In Christ, all three elements merge together, and beckon us to offer Him our trust. He proved His power over creation and death, He taught the truth about Man and God, and He demonstrated ultimate love by taking on the form of a man and allowing Himself to be crucified on a cross. It is for these reasons that I can comfortably trust Him.