The question of determinism vs free will never be resolved to everybody’s satisfaction.
The argument for free will is only based on feelings, and as Darat has pointed out, feelings are not very good arguments.
The argument against is based on the lack of something that really needs to be explained, and the complete absence of a mechanism by which free will could operate, so it is the more parsimonious explanation, but not something that can constitute a definitive answer.
We do know that free will does not work in a number of situations, because our actions can often be influenced, or forced without us knowing it. We can be influenced by sounds, light, and smells. Pheromones can make us sexually interested in others, and they can make us buy stuff we wouldn’t otherwise buy. If the brain is damaged we may change behaviour, or even personality. These facts certainly do not work in favour of free will and spirits.
When our brains makes decisions, there millions of possible inputs. Not just the biology, the situation, and previous memories, but also random effects such as a stray cosmic ray that knocks an electron out of its path in the brain. All of which makes it impossible to ever accurately predict which decision a person will make, so instead we use the closest model of brain behaviour, which we call free will.
Free will works as a model, and we know that by free will we also include behaviours that are not exactly based on really free will, such as when people decide not to do something because of the consequences, or punishment it may provoke.
People that use determinism as excuse for their behaviour are just pathetic. It is ironic that precisely by claiming they don’t have free will, they think they can do whatever they want to do out of their free will.