How do we gain knowledge of God? Barclay describes how the Greeks sought to find God through the intellectual pursuit of knowledge or through an emotional experience (I John 2:3-6, pp 40-43). I have been involved in intellectual discussions on God's existence. These usually revolve around proving God's existence. The argument would go if you can't prove God exists to the listener then there can not be a God. But the reality is that you can't prove a universal negative. Only existence can be proven through experience. Existence is not dependent on our awareness.
To prove that God does not exist means proving the universal negative for all phenomenon, the phenomenon is not God. So to prove God does not exist a person needs to have universal knowledge or experience. That is something that we don't have. To know God simply means that we have knowledge or experience of Him. There is one complication and that is what a person means or understands God to be. If a person expects a physical manifestation of God then they may never find Him.
As well as the intellectual debate, there are also the emotional experiences of Him through the charismatic movement. God floods the emotions and on occasions causes people to fall over. Yes, sometimes the falling over is because that is the expectation but not always. A focus on emotional experience can led to dissatisfaction.
Ultimately belief in God must have it roots beyond experience or claimed knowledge. As Barclay emphasises, it is our actions or what we do as a result of the relationship that matters. This doesn't do away with the intellectual understanding or the experiences of His presence but our faith moves us to act in a way that shows His love and compassion to the world. In living out the relationship, the presence of God becomes so much more real.
Barclay, W. (1976). The letters of John and Jude (revised ed.). Edinburgh: The Saint Andrew Press.