Entirely dependant upon (1) the context and particular material circumstances, (2) the aims and methods of the 'liberation movement' in question and (3) if there are, at a minimum, reasonable prospects for success.
'Liberation movement' is quite an imprecise and ambiguous term: encompassing phenomena as diverse as civil disobedience protests, passive resistance, armed revolutions and coups, guerrilla campaigns, wars of independence and terrorism.
It can also be used in a much more limited political sense to mean something benign like campaigns aiming to create a fairer society by having policies / laws repealed or revoked that somehow disenfranchise / discriminate against certain groups in society - such as lobbying for racial equality, women's liberation, LGBT rights etc.. In this 'narrow' sense, I see value in "liberation movements" and would consider them to have had a generally good success rate throughout history (i.e. as can be seen, for example, in the gradual broadening of the electoral franchise towards universal suffrage from the 1820s - 1960s in many democracies around the world).
If what you are referring to, however, is 'liberation' in the sense of 'national liberation' (i.e. an actual revolutionary upheaval and regime change, as in independence from an empire or change of political system): in principle, if enough people in a given country - as in, millions at least - feel so passionately about the state of their country that they are willing to take to the streets and protest, even in the face of reprisals from the state, then there is a good argument for supporting the right of the people to withdraw consent from their government and try to 'liberate' themselves from the current regime. (Although prudence might, in practice, suggest that action is best avoided if the prospects of success are so vanishingly slim that little is to be gained and more harm may occur if the attempted 'liberation' continues).
However, I would never - under any circumstances - support an alleged 'liberation movement' that targeted civilians or endorsed acts of terror in any way, nor ones that resort to violence for any reason other than an absolute last resort after every attempt has been made with the government to ameliorate the causes of the uprising and reach a negotiated settlement (even then, I am pretty much almost a pacifist and would expect the 'liberation movement' to seriously pursue peaceful protest and non-violence for as long as possible, unless it is practically impossible in the circumstances (hence my almost but not quite pacifism).
Generally speaking - I think political brinkmanship, consensus-building and dialogue across partisan lines should be pursued well in advance of any recourse to a concerted campaign for 'liberation', in case the underlying causes can be resolved in a less contentious fashion, without fanning the flames of greater division, unrest and polarisation in society. But if it comes to the bit, and all other sensible avenues have been exhausted and proven fruitless, "liberation movements" can become a necessity.