“No God before me” can have, and does have in the history of Christianity, three possible interpretations.

• the exclusivist one (Evangelical churches mainly): the Christian God is the only God, you have to confess him directly to be saved.
• the inclusivist one (mainly the Catholic church, and some Protestants), the Christian God is the only God, but you can unknowingly pray him when you pray an other God within other traditions, in other words you can be Christian without knowing it.
• the pluralistic one (other Protestants), most religions are equally valuable, but if you are Christian you should pray only the Christian God.

Of course this is just a model, all positions are deeper than that and most people mix two or even the three models. I don’t know where the Orthodox Churches stand.

For myself, I tend to be somewhere between the second and the third model.