Rene Descartes (1596-1650), founder of Analytical Geometry and Modern Philosophy
“I have always been of the opinion that the two questions respecting God and the Soul were the chief of those that ought to be determined by help of Philosophy rather than of Theology; for although to us, the faithful, it be sufficient to hold as matters of faith, that the human soul does not perish with the body, and that God exists, it yet assuredly seems impossible ever to persuade infidels of the reality of any religion, or almost even any moral virtue, unless, first of all, those two things be proved to them by natural reason. And since in this life there are frequently greater rewards held out to vice than to virtue, few would prefer the right to the useful, if they were restrained neither by the fear of God nor the expectation of another life.” (Descartes 1901).
2. “It is absolutely true that we must believe in God, because it is also taught by the Holy Scriptures. On the other hand, we must believe in the Sacred Scriptures because they come from God.” (Descartes 1950, Letter of Dedication).
3. “And thus I very clearly see that the certitude and truth of all science depends on the knowledge alone of the true God, insomuch that, before I knew him, I could have no perfect knowledge of any other thing. And now that I know him, I possess the means of acquiring a perfect knowledge respecting innumerable matters, as well relative to God himself and other intellectual objects as to corporeal nature.” (Descartes 1901, Meditation V).
Credit: Nobelists.net
With All I Am 
Descartes wrote a lot about God.
please explain what he means by “now that I know him, I possess the means of acquiring a perfect knowledge respecting innumerable matters, as well relative to God himself and other intellectual objects as to corporeal nature”
how can u know GOD? or is it a means of convincing yourself that there is GOD?
Hi Kay,
This is not a means of convincing oneself that there is God but a meditation(namely a day and night reflecting of the word of God “Bible”) of Rene.
Example: Imagine you are rested by the police and taken to court and facing the Judge and the jury,charged with 14:00 bank robbery. You know that between 13:00-15:00 you never left your home which is 5 hours to the bank, took a nap then after had coffee with a reporters who happen to write a story about you at your home.
When Christians give proof for existence of God(Argument for Existence of God), it is like this person who knows that there is know way he was one 14:00 bank robber.
But this truth is not known to the Judge and the jury, thus a Christian is to give a defense as this person would, namely he was home all day, and had reporters(whom some are his enemies), 5 hours drive as his proof.
This guy is not convincing himself that he was home, he knows he was home.
How do you know God? God can be know through nature, thus the Five Arguments for Existence of God.
A relationship with God is faith. Christian faith or the word faith as used in Christianity means confidence in the truth, value and trustworthiness of Historical Jesus which is rested on logical proofs and material evidences.
N.B: More on Faith and Existence of God
People confuses this truths thus I often use parables(stories) to explain.
I know my wife exist, and I have faith she will divorce me tomorrow because I am bankrupt.
Faith used here means I know from logic: how she has dealt this situation countless times, her value: she love me not because of financial statutes, trustworthiness: her character reflects the definition of the word.
Existence here mean, I know I am married to a real being that exist and I have proof of her existence namely she cook for me, has a family, work as a nurse(assuming that I am mentally healthy)
Thus these is how a Biblical Christian knows God exist and belief/ have faith in Him.
Let me know if I answered some of your objection and if not which one specific.
Prayson