1 Cor. 8:4-6 (ESV)
Therefore, as to the eating of food offered to idols, we know that "an idol has no real existence," and that "there is no God but one."  For although there may be so-called gods in heaven or on earth—as indeed there are many "gods" and many "lords"—  yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.
“There is no God but one.” Already in Paul’s day this phrase was being abused. The people were rationalizing that if there is only one God, than all people worship that one God, no matter what they called him. And on the flip side, that they were at best doing nothing than by joining others in the worship of gods that did not exist. Public pressure, and politeness urge us to join in the worship of other gods, funerals, weddings, and Masonic rituals we are invited too, often invoke the presence of other Gods. Now you might find it easy to avoid the Masonic rituals, but funerals and weddings are of another sort. I would not tell you to avoid funerals and weddings, but caution you about the impression you might give while joining in prayers. A few years ago I was invited to a National Day of Prayer breakfast. I went. But after the Mormon Bishops said their prayers, I found the best course of action was to be silent, and not go to another one. They don’t believe in the same God, or the same Jesus I do. I would not offer my prayer in a shotgun approach to pray to the true God for His blessings on this nation. There is only one God, but people still worship other so-called gods. Worshiping these is an abomination to God. They lead people away from the comfort and grace in the forgiveness of sins offered by the one true God on the cross, where God was in Christ reconciling the world. He is our only hope, we dare not give the impression that there is hope to be found outside His cross, whether by eating meat offered to another god, or offering our amen to a prayer in that god’s name.