I stress that this is my opinion.
The opposition forces fighting the Syrian Regime are not a single cohesive group but many different elements from a wide range of religious and political backgrounds. The two main Muslim factions, the Sunnis and the Shiites are on opposing sides, there are fundamentalist groups associated with terror organisations, many that are answering a call for Jihad and some opposition groups have started to launch attacks on each other. The whole situation is confusing and constantly changing.
The problem for any Western Nations contemplating intervening is; who would you help and what guarantee is there that the group that you helped would not eventually turn against you?It is actually possible that who ever eventually takes over in Syria could be more anti west than the existing government.
Surely we have learnt from the experiences of the intervention in Afghanistan after the Russian invasion, Iraq and the latest Afghani involvement.
Any intervention, based on the idea of saving lives or establishing democracy in Syria is doomed to failure and would just lead to more unnecessary loss of life.
Please let the Arab nations sort out their own problems.