A Wise Man Never Trusts Himself Completely

J.C. Ryle (from Banner of Truth):

'Let it be a settled principle in our religion, that there is an amount of weakness in all our hearts, of which we have no adequate conception, and that we never know how far we might fall if we were tempted. We fancy sometimes, like Peter, that there are some things we could not possibly do. We look pitifully upon others who fall, and please ourselves in the thought that at any rate we should not have done so. We know nothing at all. The seeds of every sin are latent in our hearts, even when renewed, and they only need occasion, or carelessness, and the withdrawal of God's grace of a season, to put forth an abundant crop...The servant of Christ will do wisely to remember these things.

"Let him that thinketh he standeth, take heed lest he fall" (1 Cor. 10:12).

A humble sense of our own innate weakness, a constant dependence on the Strong for strength, a daily prayer to be held up, because we cannot hold up ourselves, these are the true secrets of safety.'

Bottom line: the only one you can always trust is God Himself. The Bible gives us the standard against which to test our desires and motivations. It is always reliable, even when we are not. And God counsels and advises us through the Holy Spirit and prayer. But to receive that counsel, you must be often in the Word of God and spend time earnestly baring your heart to Him in prayer. You don't hear what you don't listen for. "Cease to hear instruction, my son, and you will stray from the words of knowledge." (Proverbs 19:27)