Hi Carla,
Many religious festivities and symbols have been adopted by pagans for themselves, their festivities and beliefs and it is the same in the opposite. This in itself doesn't make them right nor does it make them wrong. They are traditions of men. It is what is in our hearts that makes the difference. Do we worship Jesus Christ in truth, from the love we have for Him in our hearts or do we worship Him in appearance only.
We were given the rainbow as a reminder of God's promise to mankind. It is now used to represent that which is an abomination to God. Do we forget the purpose for which God gave us the rainbow just because of this?
The cross is also a reminder of that which Jesus Christ did for us. Crosses themselves have no power but they are a wondrous reminder of the power and saving grace of God. Crosses are now also used for many various things by mankind. Should we forget what the cross represents?
God made all that is on the earth and it is good. He gave us all trees that are good to the sight. (Gen 1:29 and Gen 2:9 ) Should we worship these things as the pagans do? Definitely not. Those things have no power, it serves no purpose to worship or to pray to these things nor to hold them up above God. The only one worthy of worship is Jesus Christ, very God.
Can we use them to remind us of the wondrous things that God has done for us and His wondrous power? There is nothing wrong in doing so. We can also look around us daily at all that God has created and be reminded in just this same manner of God's wondrous power and His saving grace.
Col 2:6 As ye have therefore received Christ Jesus the Lord, so walk ye in him:
Col 2:7 Rooted and built up in him, and stablished in the faith, as ye have been taught, abounding therein with thanksgiving.
Col 2:8 Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ.
Col 2:9 For in him dwelleth all the fulness of the Godhead bodily.
Col 2:10 And ye are complete in him, which is the head of all principality and power:
Col 2:11 In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
Col 2:12 Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
Col 2:13 And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
Col 2:14 Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross;
Col 2:15 And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it.
Col 2:16 Let no man therefore judge you in meat, or in drink, or in respect of an holyday, or of the new moon, or of the sabbath days:
Col 2:17 Which are a shadow of things to come; but the body is of Christ.
Col 2:20 Wherefore if ye be dead with Christ from the rudiments of the world, why, as though living in the world, are ye subject to ordinances,
Col 2:21 (Touch not; taste not; handle not;
Col 2:22 Which all are to perish with the using;) after the commandments and doctrines of men?
Col 2:23 Which things have indeed a shew of wisdom in will worship, and humility, and neglecting of the body; not in any honour to the satisfying of the flesh.

A tree created by and decorated by God.