Rabbi Alexander Tsykin
When we move to a new house, we usually set up power, water, internet, and immediately go to buy the things we will need to live there. Avraham Avinu doesn't take this route. Instead, upon reaching a place where he could settle down, however briefly, he immediately builds an altar. Why does he do this?
The words of the Torah answer our question. Avraham doesn't just "buil(d) an altar." He "buil(ds) an altar to G-d who appeared to him." G-d appears to Avraham when Avraham is getting ready to worship Him. We can learn an important message here. Our relationship with G-d is contingent on our effort. When we perform actions of worship, G-d appears and enters our lives. Avraham's revolutionary message to the world (one of them) is that we govern G-d's availability.
If we want Him, we can have Him. It's entirely up to us.