Neither present (mēde paristanete). Present active imperative in prohibition of paristanō, late form of paristēmi, to place beside. Stop presenting your members or do not have the habit of doing so, “do not go on putting your members to sin as weapons of unrighteousness.”
Instruments (hopla). Old word for tools of any kind for shop or war (Joh 18:3; 2Co 6:7; 2Co 10:4; Rom 13:12). Possibly here figure of two armies arrayed against each other (Gal 5:16-24), and see hopla dikaiosunēs below. The two sets of hopla clash.
But present yourselves unto God (alla parastēsate heautous tōi theōi). First aorist active imperative of paristēmi, same verb, but different tense, do it now and completely. Our “members” (melē) should be at the call of God “as alive from the dead.”