Mathew 6:24

No one can serve two masters; for either he will have the one and love the other, or else he will be loyal to the one and despise the other.  You cannot serve God and mammon.

We will serve what we trust in the most.  If we trust God to provide for all our needs, we will trust in Him. If we trust in money to provide for all our needs, we will spend our time chasing after money.  Our hearts cannot be divided over the matter.